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n^io' 







^/ '-I /y 



^^^>r-^:6ranc, 




MAP OF 



^n 



#ri 



[S OF 



IICTS 



Corrxi 



2. 



Paleozoic 



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//icf 



department (of A^-^ ra of ^Tiues. 



NEW ZEALAND GEOLOGICAL SURVEY. 

(J. M. BELL, Director. I 



^--L 






BULLETIN No. 6 (NEW Series). 



THE GEO LOG 1^ 



MIKONUI SUBDIVISION 



NORTH WESTLAND. 



PERCY GATES MORGAN. 



ISSUED UNDER THE AUTHORITY OF THE BON. JAMES HcOOWAN. MINISTER OF MINES. 







Wl\^^ 



2 8 iScO 



.r, rnO-^S LIBRARY 



NEW ZEALAND. 
BY AUTHORITY : JOHN MACKAY, GOVERNMENT PRINTER, WELLINQTON 

1908. 



7c accompany SuUetin NS 6, Mikomii Subdivision. North Weatland Division 




P^ 4000' below sea level 



Section along Line AB, Totara Survey District 




JAMES MACKINTOSH BELL 

DIRECTOR 




Section along Line DEF Toaroha & Murray Survey Districts 



Natural Scale 



Reference to Geological colours 



Recent end 
Pleistocene 



Newer fluviatile and marine gravels 

Older fluviatile and Huvio-glacial gravels.. 

Morainic gravels 

Moutere gravels 



Dra^vrv iy Q.EJIcLrris . Jujze 7308 



Upper 
Mioceni 



Eocene- 
Oligocena 



I Conglomerates, sandstones, 
I grits, grauwackea, olays, i&o.j 

IKoiterangI Series — 
Conglomerates, grits, shales with coal) 
seams, sandstones, and limestones I 



1 i_ '_'__]_ 



Greenland Series— 

Qrauwackes and arglllites. 
Arahura Series — 

3. Less metariiocplioscd 

grauwaokfls and argillit 
2. Mica schists 



1. Gneissic and dark schists 






Talo-solilsl bands ^^ 

Pounnniu formation. Dunilo, sei-pentint, talc, ic I ^^ -I 

Tuhua formation. Granitic roclis .^^^. r • -i 

Basio d,ke,-[S Q-rt. ..in....[Z] Fauit, _...[2D 



By Authority : John Maohay. 



■soo-a/oa-666 



Ti acccmpcui>- Bull f tin N'- C. Mikcmu SubdMsicn Narth Wtstlaiid Divisi. 




GEOLOGICAL MAP OF 



AND PARTS OF 



SyR¥E¥ PISTKICTS 



Scale of Chains 

I U^ l-< t-H h-I 1- 



~ Reference 

floods shown, thus 

Tracke- 

Tri^oncmetricaL StcUions-.- „ „ - C @/ef' ' 

Edges of Bush _ 

Swamp „ _ _ „_ *jt.%JB- 

Complied /rom data obtained from the Lands and Survey Department , 

yvitA. additional su.rve/s by P a Morpan 6, JASartrujTV. JAMES MACKINTOSH BELL 

of the GeoloQical. Survey Deportment 



/Newer fluvlatile and marine gravals.... 
I Older fluvlatile and fluvio-glaclal grnvels- 
\ Horolnio gravelB.-. - 



Amhura Series — 
2. Mica schists - 



— Reference to Geolo g ical Colours and Si gns 

-1- r= 



I. Gneissic and dark schtsts.. 



...IZ§ ...... ...[Z]r...,..^ 



Outcrops with observed strike and dip -^ 

no strike and dip + 

*""'"'' '"'* Qm«ied and dmwKbyRJG^ M. July 1908 



By Authority : Jotii\ Maohay. Qoutrnmani Prlnttr. 



T( atocmpany Bulletin K^ 6. Mikcnui Subc/i^isifn.Ncrth Wcstland Divisicn. 




ComfiUd and drawn by mCra-w ford, JvLTiM 1908 
By Authority r John Maoliay, eootrnmtnt Pi 



T" aceamtmnf BuUtlui N^ 6, Mikomu SuMtvtsUin. North Wtstlimd Divisiim 




GEOLOGICAL MAP OF 

mnmk suwey id strict 



Compiled. Pram, data obtained from the Lands and 

Survey DepartmeTU.. with additiunstiy PG -Morgan, 

of. the Geological Sijrvty Department. 



Giu^Htd and drawn fyRJ.Cra>vford,May f908- 



To accompany Bulletin m' 6. Mtkonai SubdMswn. North Wtsttnnd Dlvi 




1 - 63380 
— Reference to Geolo gi cal Colours and Si gni 



(Newer fluvlatlls and marine graveli I 

j Older fluvlalll 
\ Moralnk gra 



CamfiUd and drawn by QAJ)tirfy,K7Une 1908 



Oiigoeene Conglomerate*, grlte, thelai wjtli cob 

' isami, aenditonea, nnd llmealonet 



opglinios b 



3. Leie metamorphoseit 

grauweokee and arglNltes 
2. Mica gchlela 

I- GnelMic end dork icliiiti 



Tnlc-sohlsl bonds - 

Patmnmu rormellon.. Dunlte, aarpentirte, I 

Tul.un formallon. Qranlllo roska 

.... d,.....IZ§ ,„.,„ .„.._.LZ] f..„....^ 



.ES3E3 



Outcrop! with obMPved alrike and dip ^ 

no Btrlka and dip ^-i-^ 

„ varlleal dip ^ 



71 accompany Bullclin SS 6. Mikitnui SuhdirisUn, North Weslland DivL 




i 



Compiled from. data, obtained from the Lojyia 
and Survey Departrnent, and surveys agecuted 
R.P Greville. P. G. Mo rgon. ^ C.EAda, 
JAMES MACKINTOSH BELL of the Geological Survey Departmerxt. 



I Com piled rrnddroMnby (XAJ)arby.]307. 



TOPOGRAPHICAL MAP OF 

V TOAii^aA syE^fEY district 

ticale of Chains 



SEatriU'fiilr I < 



M'Bi- 
- Refex^euce ■ 



D I S T R I C T 



Edge. ofStuih, 

Swatnp - ___ 

TlWcf/itiis 

Triffonome^UaX Staiions • 

itotoitatn TeoJiB 

Hcade 

Tracks 

n^rmii-u;. 



-shown thixe — /5?3^— 

- A-jiAad 



fiy Authority ■ John Maehay, I 



^ 



To acacmpanv Bulletin N^ 6, Mikcnia SnJ>divLsicn.North\Vcstland Divi 




Scale of Chain s - 



1 : 63360 



■ Reference to Geolo g ical Colours and Si gns " 



I Newer nu«iati1e and mat 

j Older fluviBlile and nuvio-elacial era.els...- 1 | 



—L 



Pliocene Moutere gravcli-. 

Carr.flUedanddniwn.fyRJOv.wford.June 1908 



I I 



Upper I Congiomerales, sandsloncs, ] 

Miocene i grits, grauwaokcs, claya, Ac. , 



I Koilerengl Series— 
omerates, | 
I, sandstones, and lime^tonei 



(Gnenland Series— 

Qrauwaches and arglllltes 
Arnhura Series— 



.I^S 



Tiil.ua formation. Gra 



i dykes- - f^^ Quartz veins. - | / | 

Outcrops wltli observed Strike an 
,, no strike and dip 

„ vertical dip 






dip ^ 



To aeecmpany BuUrtin NS f,, Mikinui SuhUivUUri.North Wcstland. Hivi 




Roctds and Tracks shotvn. t}tLL8 

Tri^onjometricctL Stations- _ „ » - C ^iBfi' 

Ed^esofBueh 

S^vamp „ __„_ *Mi*- 

fVaixr Races 



TOPOGRAPHICAL MAP OF 



Compiled from data obtained from. th^Landt 
and Survey Department, and surveys executed by 
FGMar^an; of the Geological Survey Departm£nt. 




JAMES MACKINTOSH BELL 



Bv Ai^thorily : John Mi 



To atcompany Sidlctinirs 6, Mikomti SitldivUwn.NorthWestland J)iv 




TOPOGRAPHICAL MAP OF 

Aimk SiiWEY ilSTilCT 



;z:^K^ 



Compiled from data obtained from OieZands and 

Survey Dtpartmtnt, with additionsbyP.G.Mor^a.- 

of the Gealoffical. Survey D^cn' 



ConjpiUd and dra;wnhyRJ.Craw^Td.,May I30S. 

8y Authetitv • John Maakay, Ocutmmtnt Printtr, 



To tuocmpany SidletinN^ 6. Mikcnui Subdivision. North Westlnnd Division. 





Compiled from daXo. obtained from iheLands 
and Surv^Departmoil, tviOi. addittOTtoL 



Q^the Oeologicai Survey Depi 



GEOLOGICAL MAP OF 

\iimmm m%% mmiEi m 

AND piiTiiis or mwMk mm buju 

Scale of ChEiins 



Reference 

Edqes of Bu.sh' shown, thus ~f^-'"'^ 

■Syvamp » » — -^It^f^;^ 

WaterfalLs n „ IIj-^^: 

Roads T» n .^=1==*^ 

Tracke i 



TrigoTiometrical Stcitian.8- 

MourLtaito Pcahx 

RaUvfo^s 

TrairvLineB 



. C@/S-?/'- 



JAMES MACKINTOSH BELL 



I •■ 63360 

- Reference to Geolo g ical Colours and Si g;ns " 



I Newer fluyiatlle and marine gravels I 

■, Older fluyifltile and Iluvio-glscial gravels....^ 
Morainic gravela j^ 



By Authorilu -■ John llaoUa^. Qoufymtnt Prtnfr. 



I Greenland Series— 

Qrauwacket and arglllitas 

I Arahura Series— 
I 3. Less metatnarphosed \ 
Paleozoic e^auvaokej and argillitesj 

1. Gnelssic and dork schlsti. 



.Erni 



Talc-schist bands ., 

Pounarnu formnlion. Dunita, aerpenttne, laic, &e.. 

Tuhua formation. Granitic rocks - 

Quarti veins i -^^ I Faults 



Outcrops with observed Strike and dip -^ 

".. 11'.', Ip" " ^ 

Compiled anddra^m-hy G.EJJama .-Jufy /^ 



To a£Company Bulletin NV 6. Mikciuti Subdivt^wn. North Westland JH 




»V Aulhorltu : John Uackay. OoD«mm.nt frhltr. 



PLATE I 




BaHUOX CaXYOX, at JUXCTION OF I'UK K AM) WlllKOMliK JilVKHf 
I'holo hi/.Mi. Janni.-i I'urk, lliikitila.] 



(itol. Bull. No. H ^ 



[Fraiifi-'inirr 



With the compliments of the Honourable 
the Minister of Mines. 



Geological Survey 
of Neui Zealand 



Ill 



LETTEB OF TRANSMITTAL. 



Geological Survey Office, 

Wellington, 23rd October, 1908. 

Sir,— 

I liave the honour to submit herewith Bulletin No. (3 (new 
series) of the Geological Survey Department. 

The bulletin covers a report on the geology of the Mikonui 
Subdivision, North Westland, by Mr. Percy Gates Morgan, General 
Geologist. 

The volume contains 175 pages of letterpress. It is illustrated 
by twenty-nine plates and two diagrams, and by two general maps, 
live detailed topographical maps, five detailed geological maps, and 
one sheet of two geological cross-sections. 

I have the honom" to be, 

Sir, 

Your obedient servant, 

J. M. BELL, 

Director. 
Hon. James McGowan, 

Minister of Mines, 

Wellington 



C O N T i^^ NTS. 



Letter of Transmittal 



iii 



Chapter 1. — Geneeal Information. 



Introduction 
Area described . . 
Previous (ieological Surveys 
Plan of Work . . 
Acknowledgments 
Fauna 

Mammals 

Bird-life 

Reptiles 

Fishes 

Arthropodii 
Flora . . 

(1.) The Zone of Heavy Mixed Bush 

(2.) Plant Assemblage of the River-flats 

(3.) The Rata and Beech Zone . . 



I'ag"' Page 
1 Flora — continued. 

1 (4.) The Subalpine Zone . . !) 

2 (5.) The Alpine Meadowland 10 

2 Character of Land and Soil ..11 

3 (1.) The Modern Coastal Plain .. ..11 
3 (2.) Flood- plains of the Lower River- valleys 11 

3 (3.) Lowland River- terraces, Morainic De- 

4 I posits, Fans, &c. .. .. ..11 

7 1 (4.) Bush-clivd .Mountain-slopes .. 12 

7 1 (5.) Grazing-land above the Bush-line . . 12 
7 (<>.) Mountain Peaks and Ridges above the 

7 Grass-line . . . . . , 12 

5 Climate . . . . . . . . 12 

i» Scenery. . . . . . . . . . 15 

!» Literature . . . . . . . . lU 



Chapter II. — Culture. 



.Account of Alluvial 



Inhabitants 

Means of Communication 
Alluvial Mining Industry 
General and Historical 
Mining 
Dredging 

Method.s of working Alluvial Claims and 
Gold-saving Apjiliances 
Auriferou.s- quartz Mining . . 
Silver- mining 
Coal-mining 
Special Mining AreasJ 



20 
20 
22 

22 
24 

24 
2.") 
20 
2() 
2») 



Special Mining Areas — continued. 

Ross Flat 

Mont d'Or Gold-mining Company 

Donoghue's 
y|Mcl.*od's Terrace .Sluicing Company 
Water-races 
Gold- production . . 
Tiniljfr Indu.itry. . 
Agricultural and (irazing Industries 

Dairying 

Honey 

Fla.x .. 



20 
27 
27 
28 
28 
28 
28 
29 
29 
29 
29 



Chapter III. — Outline of the Geology. 



Sequence and General Structure of the Several 
Formations . . . . . . . . 'M 

Geological History . . . . 32 



Periods and Directions of Folding, Elevation, 
Depression, &c. . . . . 35 



Chapter IV. — Physiooraphy. 



General Features . . . . 38 

Mountains and Hills . . . . 39 

(n.) The Main Alpine Dix idc .. ..39 

(t.) Subsidiary Ranges of the Alpine Chain 39 

(c.) The Granite and (Jneiss Mountains 41 

(rf.) Outlying Ridges and Hills . . . . 41 

(e.) Morainic Hills . . .42 

{/.) The Ancient Peneplain .42 

{(/.) Mode of Formation of Alps . . . . 43 

(A.) Structure . . . . . . . . 43 

Passes and Saddles . . . . . . 44 

(1.) Passes over the Main Divide . . 44 

(2.) Saddles of the Subsidiary Ranges . . 45 

(3.) Saddles of the Ancient Gregory Valley 45 

(4. ) Saddles of the Foothills . . . . 46 

Plains, River-flats, and River- terraces . . 4(5 

Rivers . . . . . . 47 

(1.) The Hokitika River and its Tributaries 47 

(2.) The Totara River and its Tributaries . . .">(» 

(3.) The MLkonui River and its Tributaries. . 51 

(4.) The Waitaha River and it.s Tributaries. . 51 
(5.) Duffer Creek and various Lowland 

Streams . . . . . . 52 



Rivers — continued. 

(6.) The Wanganui River and its Tributaries 
Waterfalls and Cascades . . 
Gorges . . 
Grade of Rivers . . 
Hanging Valleys 
Areas of River- basins 
Volumes of Rivers 
Captured Drainage and Ancient River-courses 
Glaciers 
Glacial Erosion, Transportation, and Deposi 

tion . . 
Snowhelds 
Springs 

(o.) Cold 

(6.) Mineral 
Lakes 

Former Lakes of the Area 
Lagoons 
The Shore-line 
Fans 
Talus 
Slips .. 



52 
53 
54 
54 
55 
55 
5(i 
5(i 
58 

(iO 
(il 
(J2 
62 
62 
63 
64 
64 
65 
66 
66 
66 



VI 



Chaptee V. — FAtriiTiNG AND Wakpimg, with thetb Physiogkaphic akd Geological Effects. 



Faults of the Area 
Introductory . . 
(1.) Faults of the Main Range 
(2.) Faults of the Foothill Area 
(3.) The Great Thrust Faults 

Warping and Tilting 

Physiographic and Geological EfFects 





I'age 
. 68 




. C8 




. 68 




. 70 




. 71 




. 72 


ts 


. 73 



Physiographic and Geological Effects — contd. 

(1.) Physiographic and Geological Bound 
aries formed by Fault-planes 

(2.) Areas of Depression 

(3.) Valleys and River-courses 

(4.) Changes of Stream-grades 

(5.) Rock- basins 
General Conclusions 



Page 

73 
73 
73 
74 
74 
75 



Chapter VI. — The Aeahtea Series. 



Age and Correlation 

Distribution 

Subdivisions 

Structure 

Period of Metamorphism 

Causes of ^Metamorphism 

Thicliness of the Series 

FossUs . . 

General Petrology 

(1.) Lower Gneisses and Schists 
(a.) Gneissic Schists 
(6.) Dark Schists 
(2.) Mica-schists 

(a.) Quartz-mica-schists 



76 
77 
77 
78 
78 
79 
79 
79 
80 
80 
81 
82 
83 
83 



General Petrology — continued. 
(2.) Mica-schists — continued, 
(b.) Quartz-schists 
(c.) PhyUites 

(d.) Doubly Metamorphosed Kocks 
(3.) Less Altered Grauwackes and ArgiUites 
(a.) Subschistose rocks 
(6.) Non-schistose rocks . . 
Special Petrology 

(1.) Gneissic and Dark Schists . . 
(2.) Mica-schists 
(3.) Grauwackes 
Analyses 



84 
84 
84 
85 
85 
85 
86 
86 
94 
94 
95 



Chapter VII. — The Greeni^ajnd Series. 



Age and Correlation 
Distribution 
Structure 

Relation of Structure of Series to that of the 
Southern Alps 



96 
96 


General Petrology 
(1.) Grauwackes 


. . 97 
. . 98 


97 
97 


(2.) Argillites . . 
Special Petrology 
Analyses 


. . 98 
. . 99 
..101 



Chapter VIII. — The Koiteeangi Series. 

Content and Conditions of Deposition . . 102 Palaeontology 

Age and Correlation . . . . . . 102 General Petrology 

Distribution . . . . . . . . 103 Special Petrology 

Structure . . . . . . . . 103 



104 
104 
103 



Chapter IX. — Upper Miocene Beds. 



Content and Conditions of Deposition . . 107 

Age and Correlation . . . . . . 107 

Distribution . . . . . . . . 107 

Structure . . . . . . . . 108 



Palaeontology 
General Characters 
Special Petrology 



108 
109 
110 



Chapter X. — Pliocene, Pleistocene, and Recent Beds. 



Introduction .. .. .. ..113 

I. ilontere Gravels (Early Pliocene) . . 113 

General Account . . . . . . 113 

Age and Correlation . . . . 114 

Distribution . . . . . . 114 

Structure . . . . . . . . 114 

General Characters . . . . ..114 

Origin . . . . . . . . 114 

II. Late Pliocene and Pleistocene Deposits . . 115 

(a.) Morainic and Fluvio-glacial Gravels 115 
Age and Correlation . . . . 116 



II. Late Pliocene and Pleistocene Deposits — 




(a.) Morainic and Fluvio-glacial Gravels — 




Distribution and Lithological 




Characters . . 


116 


(6.) Fluviatile Gravels 


118 


(c.) Jlarine Gravels 


118 


III. Recent Deposits 


118 


(a.) Glacial and Fluvio-glacial 


118 


(h.) Fluviatile and Lacustrine . . ] 


118 


(c. ) Marine 


19 


(d.) Talus . . . . . . . . ] 


119 



Chapter XI. — PouNAiicr or Serpentine Formation. 



Content 

Mode of Occurrence 

Age and Correlation 

Distribution 

General Petrology 

(1.) Serpentine-dunite 

(2.) Serpentine 





. 120 




. 120 




. 120 




. 121 




. 121 




. 121 


, , 


. 122 1 



General Petrology — continued. 

(3.) Serpentine-schist 

(4.) Talc-serpentine and Talc- rock 

(5.) Miscellaneous Rocks 
Special Petrology 
Metamorphic Influence 



122 
123 
123 

124 
128 



VI 1 



Chapter XII. — The TtrmjA or Granite Formation. 







Pa?e 




Page 


Content 




. 130 


General Petrology — continued. 




Mode of Occurrence 




. 130 


Homblende-biotite-granites 


.. 133 


Origin . . 




. 131 


Aplite . . 


..133 


Age and Correlation 




. 131 


Pegmatite 


.. 133 


Distribution 




. 131 


Special Petrology 


.. 133 


General Petrology 




. 132 


Metamorphic Effects 


.. 136 


Biotite-granites 




. 133 






Chapter XIII. — The Basic Igneous Rocks of the Mikonui Subdivision. 





Mode of Occurrence . . . . . . 138 General Petrology 

General Distribution, \\'idth. Strike, and Dip Special Petrology 

of Basic Dykes . . . . . . 138 Analyses 

Age and Correlation . . . . . . 138 



139 
140 
141 



Chapter XIV. — Economic Geology and Wai ek-power. 



Metalliferous Veina of the Arahura Series 

(1.) Quartz Veins 

(2.) Pyritic Veins 
Metalliferous \'eins of the Greenland Series 
Asbestos and Talc 

Occurrences of Asbestos 

Occurrences of Talc 
Building and Ornamental Stones . . 
Limestones for Agricultural Purposes, &c. 
Road-metal 
Clays 



143 Coal 

143 Auriferous Alluvial Deposits 

144 (1.) River and Creek Gravels 
144 (2.) Fluvio-glacial Gravels 

147 (3.) Beach-sands 

148 (4.) Special Area — Ross and Neighbour 

148 hood .. 

149 (5.) Origin of Auriferous Alluvial Deposits 

149 Prospecting . . . , 
lol» Water-power 

150 Summary of Mineral Resources 



151 
151 
161 
153 
153 

153 
155 
156 
158 
161 



Appexdix. — List of Minerals found in the Subdivision, Mode of Occurrence, and Chief Localities 
Index 



163 

Kl.j 



Rainfall, &c. 
Geological Formations 
River Di.scharfres . . 



Tables. 



.14, 15 
33 

. . 57 



vni 



LIST OF ILLUSTEATIOXS. 



Plate 
I. 

II. 

III. 

IV. 



V. 
VI. 

A^I. 

VIII. 

IX. 
X. 

XI. 

XII. 

xin. 

XIV. 

XV. 
XVI. 

x\ai. 
x\T;n. 

XIX. 
XX 

XXI. 

XXII. 

XXIII. 

XXIV. 

XXV. 
XXVI. 

XXVII. 

xxvni. 

XXIX. 



Barron Canyon, at .Junction of Price and Whitcombe Rivers 

Whitcombe Pass from the North or Westland Side 

Looking up Whitcombe River Valley toward.s Wliitcombe Pass ; !Mount Louper on right 

Wilkinson River and Terminal ^Moraine of Wilkinson Glacier ; in Background Bracken Snow 
field and Blount Evans 

Mount Evans from Wilkinson Valley 

View of Price Flat (WTiitcombe Valley), showing also Hanging Valley and Falls of Price River 
Wire Rope and Cage over Hokitika River, above Whitcombe Junction . . 

View from ilathias Pass, looking West into Valley of U])])er Hokitika . . 
View from Mathias Pass, looking dowai Canyon Creek (Canterbury Side) 



Facing page 
Frontispiece. 

6 

7 



Hydraulic Sluicing at Ross United Claim 
Hydraulic Sluicing at Mont d'Or Claim, Ross 

Lake lanthe from Neighbourhood of Boat-landing 

Panorama of the Main Divide, L^pper Hokitika District 

View from Wanganui Forks to Head of Wanganui Valley 
The Lord Range as seen from Wanganui Forks 

View from Wanganui Forks up Lambert River Valley 

View, from Lord Range, of the Lambert Glacier and Mount Lambert . . 

Granite Gorge of Kakapotahi River 
Geological Survey Camp, near Hokitika Gorge 

View of Wilkinson Vallej', showing Terminal Moraine of Wilkinson, with Mount Evans 

Background 
View of Wilkinson Glacier, showing Ice-fall and Precipices 

View, from Side of Range near Cataract Creek, up ^Vhitcombe Valley towards Whitcombe Pa: 
View, from near Frew Saddle, down Valleys of Frew Creek and ^Tiitcombe River . . 

View of Mount Allen. The Waitaha Slip appears on the Right 

Looking South up Waitaha Valley to Smyth Range. Debris from Waitaha Slip on Left 

View from near Mount Mueller, showing Artist Dome, Red Lion, and Mount Evans 
View of Cliff-face near Hende's, showing Shattered Dark Schist pushed over River-gravels 

Torlessia macTcayi and Dentalium (?) sp. 

Looking South up Wanganui Valley from Hende's Ferry. 



Wilberg Range in Background 



(1.) Micro-photograph of Feldspatliic Biotite-schist. Open Creek 

(2.) Micro-photograph of Gneissoid Rock, Headover Creek 

(3.) Micro-photograph of Quartz-feldspar-schist, Gorge Creek . . 

(4.) Micro-photograph of Altered Volcanic Rock, near Second Gorge of Tuke River 

Rangitoto Range from Happy Valley 

View from Happy Valley towards sources of Kakapotahi River. . 

Part of Doctor Hill and Pigeon Hill from Neighboiu-hood of Hokitika Gorge 
Koiterangi Hill from Neighbourhood of Hokitika Gorge 

View looking South-west from a Point a little above Junction of Whitcombe and Wilkinson 
Rivers 

(1.) Micro-photograph of Serpentine-dunite, Mount Bowen 

(2.) Grain of Chromite-magnetite embedded in Antigoritic Serpentine . . 

(3.) Arenaceous Foraminiferal Limestone, Smyth Creek 

View- of Mount O'Connor from Mount Inframeta, showing Falls in Serpentine Creek 
Mount Inframeta from \Vhitcombe Valley . . 

(1.) Micro-photograph of Homblende-camptonite from Dyke in Supply Creek Granite 
(2. ) Micro-photograph of Olivine-diorite from Loose Boulder in Shadow Stream . . 
(3.) Micro-photograph of Basaltic Rock, Humbug Creek 

View, looking West of South from Jloimt Meta, showing part of Lange Range . . 
View, looking West from Mount Meta, of Slopes of Mount Bowen 

View from Meta Range up Mungo Valley, Head of Vincent Creek, with Kea Pass in Distance 152 



16 
17 

20 
21 

28 

34 

38 

42 
46 
52 

60 

61 

66 

72 
80 



92 



96 



•104 



112 



122 



123 



140 



144 



View looking South from Cedar Flat to Head of Toaroha. Mount Ross in Background 
Omatane Canyon, (Upper) Hokitika River . . 



160 



IX 



DIA.GBAMS. 



Profiles of Cropp and Waitaha Rivers 
Profile of Toaroha River 



I'age 

49 

159 



MAPS. 



1. Map of New Zealand, showing Land Districts and Divisions . . 

2. Map of North Westland Division, showing iSurvey Distrirts 

veyed .... 

3. Geological Map of Totara Survey District 

4. ,, Toaroha Survey District 

5. ,, Murray, Waitaha, and Clifton Survey Dist 

6. ,. VVhitconibe Pass Survey District 

7. ,, Mount Bonar Survey District 

8. Topographical Map of Totara Survey District 

9. ., Toaroha Survey District 

10. ,, Murray, Waitaha, and Clifton Survey 

11. „ Whitconibe Pa.ss Survey District 

12. ., Mount Bonar Siirvev District 



and Area Geologically Sur 



Distric 



Facing page 

X 



In portfolio. 



(iEOLOGLCAL SECTIONS. 



(1.) Section along line AB. Whitcombe Pass and Totara Survey [-)istrict8 
(2.) Section along line CDEF, Totara. Toaroha, and .Murray Survey Districts 



111 porltolio. 



11 — Mikonui. 



CORRIGENDA 



Geological Map of Toaroha Stirvey District. — The isolated band of talc-schist north of Muriel Creek 
ought to be shown about three-quarters of a mile to the east of the position on map. 

Geological Map of Murray Survey District. — The more easterly of the two small outcrops of Pounamu 
ormation towards the moath of the Gropp River ought to be deleted. 

The line separating the less metamorphosed grauwackes and argilhtes of the Arahura Series from 
the mica-schists is affected by cross-faulting to an extent probably impossible to determine. West 
of the Whitcombe Valley Fault, for instance, it is moved to the north. 




By Authority : John Mackay, Govemmtnt Pnnttr. 



BULLETIN No. 6 (NEW SERrES). 



THE GEOLOGY 

OF THE 

MIKONUI SUBDIVISION, 



NOBTH WESTLAND. 



CHAPTER I. 



GENERAL INFORMATION. 



Introduction 


Page 
1 


Flora . . 


Page 

7 


Area described 


1 


Character of Land and Soil 


. 11 


Previous Geological Surreys 
Plan of Work 
Acknowledgments . . 
Fauna 


2 

2 

3 

. 3 


Climate . . 
Scenery . . 
Literature 


. 12 
. 15 
. 16 



iNTRODUCnON. 

The present publication will deal with the general and economic geology of the Mikonui Sub- 
division, which forms the southern part of the North VVestland Division. This area, except 
in the neighbourhood of Ross, has previously received little attention from New Zealand 
geologists, but the inauguration in 1905 of systematic field-work in the adjoining Hokitika 
Subdivision necessitated an extension of the geological survey to the neighbouring area. 
Field-work in the Mikonui Subdivision was accordingly begun by the writer in November, 
1905, and was continued, except during the winter and short periods when other work claimed 
attention, until March, 1908. The writer was assisted in the field-work during three months 
of the season 1905-6 by Mr. A. M. Finlayson, M.Sc. ; for a similar period during 1906-7 by 
Mr. J. Ritchie, M.A. ; and from about the middle of December, 1907, until the close of field- 
work in 1908 by Mr. J. A. Bartrum, M.Sc; who, after the writer's departure from the field, 
continued operations in the southern part of the Wanganui watershed. The topographical 
work in the Toaroha and Murray survey districts was under the control of Mr. R. P. Greville, 
departmental topographer, who explored and mapped a considerable area of extremely rugged 
and previously little-known countrj' in the watersheds of the Toaroha, Upper Kokatahi, and 
Upper Hokitika rivers, which extended into the Whitcombe Pass Survey District, besides 
doing much detailed work in the more accessible portions of these districts, and revising the 
older work where necessary. 

Area described. 
The area reported upon in this bulletin includes all that part of the North Westland 
Division which lies south of the section of country described in the Hokitika Bulletin.* It 



* Bell, J. M., and Fraser, C. : " The Geology of the Hokitika Sheet, North Westland Quadrangle," Bull. 
No. 1 (New Series), N.Z.G.S.. 1906. 

1 — Mikonni. 



2 

embraces the survey districts of Totara, Toaroha, Murray, VVhitcombe Pass, Mount Bonar, 
Waitaha, and Clifton, comprising altogether an area of nearly 700 sfjuare miles. In addition 
an area of about 60 square miles in the Wataroa Subdivision of the South Westland Division 
has been included in the maps, and is described in this report, the reason being that this area 
forms the more accessible portion of the southern part of the Wanganui River watershed, 
and can be most conveniently reported upon in connection with the northern portion which 
is in the Mikonui Subdi^^sion. 

The area under discussion is therefore bounded on the north by the southern boundary 
of the Hokitika Subdivision ; on the south by an irregular line which forms in general the 
southern boundary of the Wanganui watershed, the Lambert and its tributaries excluded ; 
whilst on the east, or rather south-east, another irregular line — the main di\'ide of the Southern 
Alps — is the boundary. Finally, on the west the waters of the turbulent Tasman Sea impose 
a natural limit to the steps of the geological investigator. 

Previous Geological Surveys. 

In 1865, soon after the discover}- of payable alhmal gold in Westland, the late Sir Julius 
Von Haast traversed the district, following the coast-line for the most part. In the course of 
his explorations he \'isited the granite gorge of the Hokitika River, and made some examina- 
tions of the Palseozoic rocks near Ross. At a later date he also reached the main di\'ide 
at W^hitcombe Pass from the Canterbury side. In his well-known work, " The Geology of 
Canterburv and Westland," Von Haast makes many valuable observations concerning the 
geologv of Westland. His interesting account of the morainic deposits in the Mikonui Sub- 
di\asion mav be specially mentioned.* 

In 1867 the late Sir James Hector visited the chief mining districts of Westland. and 
subsequentlv wTote a report, of which only an abstract has been seen by the writer.j 

A few years later, Mr. S. H. Cox, at that time a member of the New Zealand Geological 
Survey stafi, but now Professor of Mining at the Royal College of Science (London), accom- 
panied by Mr. Alex. McKay, made a reconnaissance survey of the whole of Westland. In his 
reportj Cox makes somewhat meagre references to the geology of the Mikonui Subdi\'ision. 
In subsequent publications he briefly describes some of the auriferous deposits near Ross.§ 

In later vears McKay \-isited North Westland on several occasions, but did not proceed 
further south than the Mikonui River. In 1893 he published a report|| entitled " Geological 
Explorations of the Northern Part of Westland," containing a geological map, on a scale of 
about four miles and a half to the inch, of North Westland as far south as the Mikonui River. 
McKav's discussion regarding the origin of the auriferous deposits of this area is of great 
interest and value, and his conclusions must be accepted as in general substantially correct. 

In 1895 Messrs. H. A. Gordon and McKay traversed the mining districts of Westland 
north of the Mikonui River. In a joint report McKay's conclusions of 1893 are, with 
slight modifications, reaffirmed, and further evidence in support of his \-iews is given.^ 

Plan of Work. 

Of great importance in a geological survey is an accurate topographical map on which 
to base the geological detail, and therefore particular attention was given to this branch of the 
work. In the survey of the Mikonui area large use was made of maps published by the Lands 
and Survey Department, and of data specially supplied by the Hokitika Lands Office. 

* " Geology of Canterbury and Westland," 1879, pp. 93, 393. 

■f "Abstract Report on the Progress of the Geological Survey of New Zealand during 1866-67." 
I " Report on Westland District," Rep. G.S. during 1874-76. vol. is, 1877, pp. 63-95. 
S Rep. G.S. during 1882, vol. xv, 1883, pp. 52, 53 ; and Rep. G.S. during 1883-84. vol. xvi. 1884, 
pp. 88-90. 

li See ]\nues Report, 1893, C.-3, pp. 132-186 : also Rep. G.S. during 1892-93. vol. xxii. 1894. i>i). 11-50. 
% " Miaing Reserves, Westland and Nelson," Mines Report, 1896, C'.-9. 



As already mentioned, a considerable area was surveyed in detail by Mr. Greville. Else- 
where the data obtained from the Survey Department were supplemented as much as possible 
by surveys made by the members of the geological survey-party. Bearings were taken by 
prismatic compass, and distances measured either by the chain or by pacing, the former 
method being used in the case of the larger streams. Numerous points were fixed, or their 
positions checked by cross-bearings. It is believed that the geological details have every- 
where been located with an accuracy more than sufficient for the scale on which the maps are 
plotted — namely 1 in. to the mile. Especially in the Totara and Toaroha survey districts 
the geological and topographical information has been made as full as possible. 

In carrying out the field-work, main camps were established as circumstances demanded 
at convenient points, and from these as centres exploration was conducted in various directions 
by means of subsidiary- camps on the mountain-slopes or far up the river-valleys. In all, over 
forty camps were occupied by the geological party alone during the course of the survey. 
Owing to the practically complete absence of even rough horse-tracks in the back country, 
pro\'isions, tents, and instruments had to be carried by manual labour into the remotest parts 
of the mountain-ranges. In order to gain access to the head-waters of the various streams, 
many miles of foot-tracks were roughly cut or blazed. The rivers were forded, and precipi- 
tous faces scaled, often with difficulty and no little personal danger. 

Acknowledgments. 

The information obtained from the Lands and Survey Department has already been 
acknowledged, but special mention must be made of the kindly assistance of Mr. G. J. Roberts, 
Chief Surveyor and Commissioner of Crown Lands, Hokitika, to whom more than any one 
else the writer is indebted for general information concerning the Mikonui Subdivision. Much 
topographical detail has been derived from unpublished surveys pcnsonally executed by Mr. 
Roberts many years ago, and freely placed by him at the disposal of the Geological Survey. 

Except where otherwise stated, all the assays and chemical analyses in this report were 
made by Dr. .J. S. Maclaurin, Dominion .Analyst, and his staff, to whom the thanks of the 
writer are due for the accuracy and completeness of the results supplied. 

The writer is indebted also to Mr. .Tames Park, of Hokitika, for several fine photograj)hs 
which have been reproduced in this bulletin. 

It is fitting also here to mention the help given in the prosecution of the survey by the 
various field emplovees, all of whom showed a keen interest in the work, and faithfully executed 
the arduous duties required in traversing the r()ui.'li. un.settled country which composes the 
greater part of the Mikonui Subdivision. 

Fauna. 

As is well known, the vertebrate land fauna of New Zealand other than birds is extremely 
limited. This is easilv explained by the isolation of the coiintr\- from continental land masses : 
an isolation, however, which did not prevail during past geological periods, or at least has 
been broken more than once, as this very fauna helps to prove. 

Mammals. — In the Mikonui Subdivision indigenous mammalian life is represented only by 
the long-tailed tjat {ChaUnolohus morio). which is not uncommon in the more open parts of the 
river- valleys, notably those of the Toaroha, Whitcoml)C, and Waitaha, where it was frequently 
observed towards dusk. 

Besides the usual domestic animals, several European mammals have been introduced acci- 
dentallv or by design, and are now found in the di-strict in a feral condition. The list includes 
the black rat, mouse, rabbit, and weasel, the last named being, unfortunately, only too plenti- 
ful almost evervwhere. Indications of hares were observed at a high altitude in the valley of 
Brunswick Creek ; and in the valley of the Whitcombe, above Price Flat, at an elevation of 
about 4,500 ft., a hare was actually seen. These animals must have crossed the main divide 

1'- Mikonui. 



from the Canterbury side in the one case by way of Mungo Saddle, which has an altitude of 
5,950 ft., and is nearly always covered with snow, and in the other by way of WTiitcombe Pass 
(altitude 4,025 ft.). 

Some years ago four Canadian moose were liberated near the granite gorge oi the Hokitika 
River. One of these animals, a female, was frequently seen by members of the Geological 
Survey parties during 1906 and 1907 near the junction of the Hokitika and Whitcombe livers. 
The other three, it is to be feared, have perished. 

Bird life. — It mav be regarded as well established that about the beginning of the Ter- 
tiarv era New Zealand was part of a continental land mass stretching northward beyond 
New Caledonia and Fiji as far as New Guinea. Most of our birds came during this period 
from the northern part of this continent, which may have extended through the Malay Archi- 
pelago to the continent of Eurasia. Towards the end of the Eocene the land bridge was 
broken, never to be replaced, and in consequence New Zealand birds have developed insularity 
to a remarkable and most interesting extent. 

New Zealand's v,onderful a\'ifauna is well represented in the Mikonui Subdi\-ision, the 
flightless kiwi and weka and the notorious kea being, perhaps, the most notable ; but, though 
there is still a considerable variety of bird-life, it is by no means so plentiful as in former years. 
The same observation applies to many other parts of New Zealand. This comparative scarcity 
is in part the inevitable result of bush-clearing and settlement ; but such an explanation cannot 
apply to the forest areas of which the greater part of the subdi\-ision still consists, and there 
are probablv other causes at work tending to diminish the amount of bird-life in this part of 
New Zealand 

As regards the flightless birds, the reduction in numbers is undoubtedly due mainly to the 
ravages of that imported pest, the weasel, which devours the eggs and the young birds. It 
has been stated more than once in the public press of the Dominion that this scourge, alike 
of the bush and of the cleared lands, frequently climbs trees in pursuit of food , robbing nests 
of eggs and voung, and is therefore the cause also of the decrease in numbers of the birds 
endowed with powers of flight. 

The South Island thrush (Turnagra crassirostris), a bird of about the same size as the 
European thrush, and of somewhat similar appearance, was seen only in the valleys of the 
Toaroha and Wanganui rivers. In the latter locality this bird is not unconunon. It possesses 
a pleasing variety of notes, and is indeed one of the best of our New Zealand songsters. 

The South Island robin (Miro australis) was very rarely seen, but when he did appear 
proved to be extremely friendly, though his social qualities were somewhat marred by an 
inordinate desire for the camp butter. 

The tomtit {Petrnpca macrocephala) is not a common bird in the district, but both the 
black and pied fantails (Rhipidura fuliginosa and R. flabellifera) frequently appeared in the 
neighbourhood of our camps. 

The ground-lark, or pihoihoi {Anthus novcB-zealandice). is now as scarce in Westland as else- 
where in New Zealand. 

The Uttle bird variously called by the European settler white-eye, silver-eye, wax-eye, or 
blight-bird (Zosterops ccerulescens) is seen now and again in the Westland bush. This bird 
was not known in New Zealand before the year 1856. It is an Australian bird, and is believed 
to have been blown across the Tasman Sea about the date named. Its Maori name, " tauhou," 
meaning " stranger," alludes to its recent appearance in New Zealand.* 

The dark-plumaged tui (Prosthemadera novce-zealandice) is fairly common all over the lower 
river- vallevs. This bird has fine silvery notes, and possesses the power of imitating the calls 
of other birds. Both in this respect and in song-power, however, it must yield the palm to 
the bell-bird, or makomako {Anthornis mdanura). This bird, the finest songster of the New 
Zealand bush, is now rarely seen in Westland. 

* Hutton and T)rmnmond : " Animals of New Zealand " (published by Whitcombe and Tombs), 1904. p. 98. 



Tlie little rock-wren {Zenicus gilviventris) is not uncommon in the upper river-valleys, 
and on the mountain-slopes even above the bush-line. Its extremely short tail gives the bird 
a rather ludicrous appearance. 

The kingfisher (Halcyon vagans), a silent bird, which, as Hutton and Drummond say, 
despite its beautiful plumes, conveys to one an impression of moroseness and gloom as it sits 
on its perch over some stream, is occasionally seen on the banks of the lowland streams. 

A bird remarkable by reason of its migratory habits is the long-tailed cuckoo, kohoperoa 
or koekoea {Vrodijnamis taitensis). It is a handsome bird, but possesses a peculiarly harsh 
strident cry, which it often utters during the day, as well as towards evening. Hutton and 
Drummond state that the koekoea is generally silent during the daytime,* but this is liardly 
the case in Westland. It is, however, a rather shy bird, and during the day seems, as a rule, 
to conceal itself in the depths of the forest. It arrives in Westland about the end of October, 
and leaves about the end of February', always choosing settled weather for its departure. The 
earliest date on which the call of this bird has been heard by the writer in Westland is 2nd No- 
vember, and the latest 2nd March. It is believed that the kohoperoa migrates to New Guinea 
and to the Solomon and other islands of Polynesia by way of New Caledonia.t 

The extraordinary length of flight re(|uired in this migration of the cuckoo from land to 
land (over 900 miles) is one of the links in the chain of evidence showing that land of con- 
tinental dimensions once stretched north-west and north from New Zealand towards New 
Guinea and the islands of the Southern Pacific. 

The harsh call of the kaka (Xestor meridionalis) is often heard in the neighbourhood of the 
rata forest, especially towards evening, when the bird is retiring to rest. The kaka is a gre- 
garious bird, and is hardly ever seen alone. Occasionally he emits a brassy, but not altogether 
unmusical note, which by its unexpectedness never fails to arrest the hearer's attention. 

The kaka's near relative, the kea {Nestor notabilis), is almost the only bird besides the 
little rock-wren found above the bush-line. He is pre-eminently the bird of the mountains, 
and in Westland is monarch of all he surveys. He is frequently seen at all altitudes, from 
2,500 ft. to the line of peqietual snow. Sometimes, also, especially during bad weather, he 
descends into the lower river- valleys. Like the kaka, the kea is a gregarious bird. He is of a 
bold and inquisitive disposition, often coming within arm's reach of the alpine climber. His 
handsome red and green plumage attracts favourable attention, but his raucous cry soon renders 
him obnoxious. In Westland his principal food is furnished bv the berries of the sui)alpine 
shrubs. On the eastern side of the Alps the kea has made himself notorious by his evil habit of 
attacking sheep ; but since sheep are hardly ever pastured on the Westland mountains, he may 
there be pronounced innocent of any evil penchant for kidney-fat or mutton. Finally, it should 
be mentioned, as one of the kea's good points that on the numntains when other meat is lacking 
he furnishes an acceptable addition to the camp-food, making a more than passable stew, 
with a characteristic fiavour, described by his admirers as extremely fine. 

The only other bird of the parrot family besides the kaka and the kea seen in the Mikonui 
Subdivision during the course of the geological survey was the green parakeet {Cyanoramphus 
novcB-zealandicE). This bird, now rather rare in Westland, was observed in one or two localities 
during the summer of 1906-7. 

The species of owl known as the morepork, or rurn (Ninox nov(B-zealandi(r), is found 
everj'where in the lowland country, and was often seen at nightfall flitting noiselessly about 
the outskirts of the bush. The morepork has probably more than held its own of late years, 
the introduction of rats and mice having made a doubtless welcome addition to its natural 
food-supply. 

The beautiful white-breasted pigeon (Hemiphaga novfB-zealandia;) is not as plentiful in the 
Mikoimi Subdivision as might be expected. In some locaUties, however, numerous pigeons may 
be seen during the summer, but apparently they disappear towards winter. 



"Animals of New Zealand," p. 120. \ Loc. cil., p. 127. 



6 

The South Island woodhen, Maori hen, or weka [Ocydromus auMrcdis) is a bird allied to the 
rails, which, though possessing small wings, has altogether lost the power of flight. Although 
much reduced in numbers, the weka is still found almost everywhere in the bush, and one or 
more hardly ever fail to turn up whenever a camp is pitched. By reason of its fearless, not to 
sav impudent, wavs, this bird claims much of the bush-dweller"s attention, and furnishes him 
with endless amusement. When properly cooked the weka afiords excellent eating. 

A rarely seen swamp bird, known locally as the swamp-thrush, is perhaps the swamp-rail 
or putoto {Porzana tabuensis). 

The swamp-hen, or pukeko (Porphyrio melanotus), a handsome bird of the rail family, 
is now rather scarce in North Westland. Another swamp bird, the bittern {Botaurus poecilop- 
tUus), is still rarer, onlv one or two specimens having been seen during the course of the surA^ey. 

The extremely rare white heron or kotuku (Herodias timoriensis) was not actually ob- 
served in the Mikonui SubdiA^sion, but a single specimen has occasionally been seen in the 
neighbourhood of Kanieri. a few miles outside the bouudar}- of the area. 

An interesting little bird which we found nesting in some numbers on the debris slopes 
of the great slip near the upper end of the Waitaha Settlement is the banded dottrel {Octho- 
dromus bicuwtus). The young, after being hatched, appear to be carried about by the old 
birds for some days until they are able to run. Such is the perfection of their protective 
colouring that it is difficult to distinguish the yoimg dottrels from small lichen-covered 
stones, even at a distance of only a few feet. When one comes across a brood, the 
young ones, if able to do so, run in various directions for a few yards, and endeavour to 
escape detection by squatting close to the ground, whilst the old birds, by darting to acd 
fro, and uttering repeated cries, do their best to distract one's attention from their ofispriug. 

The birds commonly found near the seashore include red-bills (probably Hamatopus 
unicolor), godwits {Limosa novcB-zealandice), and sandpipers (Heteropygia acuminata). 
Among the web-footed sea-birds are various species of gulls, terns, and petrels. 

The black shag [Phalacrocorai carho) and several other species of cormorant may occa- 
sionallv be observed about the lakes and rivercourses in the lowlands. They are perhaps 
most abundant near the mouths of the rivers. Some of our Xev\- Zealand species of Phala- 
crocorax are identical with or closely allied to Australian forms, whilst others have affinities 
with Patagonian species.* 

The beautiful paradise duck [Casarca variegata) is not common in the .subdi\4siou, except 
on the Lower Wanganui River bed, where one or two fairly large flocks were noticed. 

The grey duck (Anas superciliosa), grey teal {Nettion castaneum), and black teal {Fidigula 
novcE-zealandice) are found, but not in great numbers, in the rivers and lakes of the lowland 
countrv ; whilst the upper portions of the rivers, but more especially the smaller branches, 
are inhabited by the blue duck, or whio [Hymenolcemxis malacorkynchus). Generally only one 
pair, \vith their young offspring, is found in each stream. 

The kiwis, flightless birds of extremely peculiar type, but more closely allied to the stru- 
thious birds than to any other order, are supposed to be diminishing in numbers : but though, 
owing to their nocturnal habits, none were actually seen by members of the Geological Survev 
parties, their frequently repeated calls were heard at every camp in the main river-valleys up 
to elevations of 2,500 ft. The particular species so frequently heard by us was probably 
the grey kiwi (Apteryx oueiii). Possibly the southern kiwi, or rowi (A. australis), also exists 
in the Mikonui SubdiA'ision, but the booming call of the great spotted kiwi, or roa (A. haasti), of 
South Westland and Western Nelson, was never heard. 

Introduced birds are as yet not very plentiful in the Mikonui SubdiA-ision, but European 
larks, sparrows, starlings, blackbirds, thrushes, goldfinches, linnets, and yellow-hammers 
mav be seen in the settled areas. Black or AustraUan swans are occasionally seen in small 
flocks on Lake lanthe, about the Wanganvii River, dscc. 



* For au interestixig discussion concerning the origin of >."ew Zealand cormorants, causes of variation, 
&c., see "Animals of New Zealand," pp. 286-294. 



PLATE II. 




WiiiKOMiiE Pass (^,02.") kt.; fhom thk Xoinii ok \Vksti,.\M) Siuk. Paist ok Akkuw >.\uiii I{a.\(;k 

(i'ANTEUItUKY) IX UISTANC);. 
I'hofo I, J Mr. J(im,.< /'ark.] 



. (itoh Hull. So. i;.-\ 



[To fort pad'' 1). 



tiepliles. — Reptiles are scantily represented in the Mikonui area by one or perhaps two 
species of lizard (Lygosoma smithii and L. moco) which, so far as observed, occur only near 
the sea-beaches. 

Fishes. — The list of fish inhabiting the lakes and rivers of the subdivision is not a long 
one. Eels of several species are plentiful in the lowland streams and lakes, but shun the 
cold snow-fed rivers, though not altogether absent from the lower reaches, where the water 
is somewhat warmer, and food probably more plentiful. The native grayling is now exceed- 
ingly scarce. Mountain trout — small spotted fish 5 in. or 6 in. in length — are fairly plentiful 
in some of the smaller streams. In the spring whitebait in countless numbers invade the 
rivers from the sea, and make their way perhaps ten or twelve miles inland. Flounders, 
together with on^or two other estuarine fish, are found in the salt lagoons and brackish reaches 
near the mouths of the various rivers. A few small species such as minnows and bullheads 
complete the list of native fish. Rainbow trout have been placed in several of the streams, 
and appear on the whole to be doing well. 

Arthropoda. — The insect-life of the Mikonui area is as abundant and varied as in any other 
part of New Zealand. No attempt can be made here to give even the barest list, but a few 
species which in some way or other attracted special attention may be mentioned. During 
sunmier and early autumn mosquitoes are only too plentiful in the bush, more particularly 
where the ground is swampy. Near the watercourses and on the sea-beach sandflies abound 
all the year round, and are particularlv annoying when rain is approaching. On the mountain- 
slopes these insect-plagues are seldom in evidence, though mos(|uitoes were once or twice seen 
at elevations of nearly 3,000 ft. Blowflies are troublesome at all heights up to the snow-line. 
Small butterflies and moths are not uncommon near the snow-line, and at lower levels there 
is a considerable variety. 

Of interest to the naturalist are the large spiders which live among the stones on the river- 
beds. These spiders, unlike the ordinarv species, apparently do not make webs to entangle 
their prey. One wonders how thev get a livelihood, and what they do during the frequent 
floods, when their haunts become covered by several feet of turbulent muddy water. Near 
the snow-line one encounters similar but smaller spiders, living among l)roken masses of rock, 
where there is no vegetation save a few lichens, and little other life to be seen. 

Flora. 

For manv vears it lias been recogni-sed that a knowledge of the New Zealand flora, like 
that of the fauna, is of importance to the geologist, as indicating former land-connections 
with Australia and with South .\merica. During the past decade, moreover, the study of 
plant-life from an (ecological point of view, as inaugurated by Dr. L. Cockayne, has inci- 
dentally thrown nmch light not only upon botanical problems, but also upon the geological 
historj' of New Zealand. 

To the field botanist VVestland is one of the most interesting di.stricts in New Zealand, 
because here, to a much greater extent than in anv other part of New Zealand, except in south- 
western Otago. the native flora may be seen in its original coiidition. It is practically only 
where the bush has been felled and burnt that introduced plants have displaced the indigenous 
inhabitants to any large degree. When such a clearing after being grassed is left to itself, 
it is but a few years before a thick growth of native shrubs and small trees fills the abandoned 
clearing, making it plainlv evident that in the course of half a century or le.ss the land will 
return to a state of dense bush, with verv nmch the same assemblage of plant-life as it originally 
possessed. This rapidlv acting tendency to revert to a state of nature is due to the heavy 
rainfall, which is far more favourable to the growth of native shrubs and forest-trees than to 
the introduced plants, which are, as might be expected, largely herbaceous. 

Outside of the artificial meadows, which in the Mikonui Subdivision bear a very small 
proportion to the land in a state of nature, five zones or assemblages of plant-life may be 
recognised. These are, — 



(1.) The zone of heavy mixed bush, from sea-level to 1,500 ft. 
(2.) The plant assemblage of the river-flats. 

(3.) The rata and beech zone, extending from ],500ft. to 3,000 ft. 
(4.) The subalpine bush zone, extending from 3,000 ft. to about 3,600 ft. 
(5.) The alpine meadowland, from 3,600 ft. to the line of perpetual snow at 6,000 ft. 
to 6,500 ft, 

(1.) The Zone of Heavy Mixed Bush. — This zone supplies all the timber for the Westland 
sawmills. Wherever the ground is flat or the slope gentle, rimu, or red-pine (Dacrydium 
cupressinum), is the most common tree, and contributes fully 90 per cent, of the timber ex- 
ported. Other trees more or less milled are the swamp-loving kahikatea, or white-pine (Podo- 
carpus dacrydoides) ; matai, or black-pine [P. spicata) ; miro (P. ferrugineu) ; and totara 
{P. Mam). 

The most notable tree of the Westland forest, however, is none of these, but the silver- 
pme (Dacrydium colensoi var. tcestiandicmn), a slow-growing tree of moderate size, which is 
found chiefly in sw-ampy ground, and yields an extremely durable timber, largely exported 
to other parts of New Zealand for use as railway-sleepers. 

The timber of the yellow-pine (D. intermedium) can hardly be distinguished from that of the 
silver-pine, and is said to be even more durable. 

Besides those already enumerated, other common forest-trees, many of them useful for 
firewood, fencing, and other purposes, are the southern rata {Metrosideros luxiida) ; kamahi, 
or so-called red-birch (Weimannia racemosa) ; white-birch, or beech {Nothofagus menziesii) ; 
black-birch, or beech [N. solandri) ; kawahaka, or cedar (Librocedrus bidwUlii) ; hinau 
{Elceocarpus hookeri) ; tanekaka {PhyUocladus alpinus) ; broadleaf [Griselinia littoralis) ; 
lancewood, or horoeka (Pseudopanax crassifolium) ; manuka {Leptospermum scoparium) ; 
makomako {Aristotelia racemosa) ; ribbonwood [PPigianthus betulinus) ; " red maple " ; and 
white maple (Carpodetus serratus). 

Along the banks of the smaller streams the most common trees are the fuschia, or kotuku- 
tuku {Fuchsia excorticata), of South American affinities ; tutu {Coriaria ruscifolia), a remarkable 
plant with its nearest allies in South America ; koromiko ( Veronica salicifolia and other 
Bpecies) ; akeake (Olearia avicennicefolia and 0. ilicifolia) ; and one or more species of that 
curious genus Carmichcdia. 

The forest undergrowth consists of a great variety of shrubs, creepers, and ferns, which 
by their luxuriant growth give the bush a semi-tropical appearance. In most parts of the 
bush the underscrub forms a dense tangled mass, difficult to traverse, and is of such rapid 
growth that tracks cut through it quickly become overgrown and troublesome to follow. 

Among the more common shrubs and creepers of the forest are the five-finger, or patete 
{Schefflera digitata) ; pepper-tree [Drimys axillaris and D. colorata) ; hupiro, or karamu [Co- 
prosma foetidissima) ; bush-lawyer (Rubus australis) ; supplejack {Rhipogonum scandens) ; 
clematis {Clematis indivisa and other species) ; and kiekie {Freycinetia banksii). 

The Westland bush contains such a wealth and variety of ferns that it is impossible to 
give any adequate description in the present report. Tree-ferns are very common below 
altitudes of 700 ft. or 800 ft., the chief species represented being the ponga {Cyathea dealbata). 
The stately king fern, or mamauku {Cyathea medullaris), though common farther north, is rare 
in the Mikonui Subdivision, and was seen in only three localities. 

A very beautiful plant is the Prince of Wales's feather, or crape fern {Todea vuperba). This 
fern grows abundantly in many parts of the bush, and affords excellent food for cattle. 
Another beautiful fern is the kidney fern {Trichomxines reniforme), which is generally found 
growing on tree-trunks and fallen logs in damp situations. 

Several fine species of lycopodium grow in many parts of the forest. There is a great 
variety of mosses, some growing on the ground, others covering the trunks and branches of 
the trees with a thick growth. 



9 

(2.) Plant Assemblage of the River-pits. — The vegetation of the flats and lower terraces 
bordering the larger streams presents certain characteristics connected partly with the natm-e 
of the soil and subsoil and partly with the manner in which the rivers alternately build up 
and destroy their flood-plains. 

Those portions of the flood-plains which are of comparatively recent origin are destitute 
of trees and shrubs of any size. They support a vegetation composed of New Zealand flax 
{Phormium tenax), tussock (Poa caespitosa, &c.), toetoe (Arundo conspicua), a,nd native grasses. 
In some places introduced grasses, such as white-clover, have gained a footing. When the soil 
is poor and dry, stunted tussock, small herbs, and a dwarfed Coprosma with a blue berrv form 
the vegetable covering. 

The older river-flats are more or less densely covered with akeake {Olearia amcenmcefolia; 
0. ilicifolia, &c.) and mingimingi, or black scrub (Coprosma propinqua), to the exclusion of 
almost ever)' other plant. As the age of the flat increases, other shrubs and trees make their 
appearance. In some situations the palm-like cabbage-tree or ti (Cordyline australis) is fairly 
common. Kowhai {Sophora ietraptera) is very rare. The occurrence of this tree in Lord- Howe 
Island, Easter Island, Juan Fernandez, and Chili is a fact of deep geological significance. 
Where a deep silt forms the soil, ribbonwood, or lace-bark (Plagianthus heiidinus), becomes 
the principal tree, growing to a height of 50 ft. or more, and is regarded by the settlers as an 
unfailing indication of good land. A further stage in the age of the river-Hat is shown by its 
being covered by the characteristic mixed forests of the lowlands. This may be taken as proof 
that such a flat has been in existence for several centuries. When once covered with heavy 
bush a river-flat is not easily destroyed, because when it is attacked by the river the large trees 
that fall into the stream act as natural protection- works to the bank. 

The small flats which occur here and there in the river-valleys among the mountains have 
plant assemblages somewhat similar to those of the flood-plains of the lower feaches, but 
there is a noteworthy proportion of plants characteristic of the alpine and subalpine zones — 
for example, the mountain-buttercup {Ranunculus godleyanus), mountain-ttitu (Coriaria ancjus- 
tissima), and the needlewood (Dracophyllum longijolium). 

The lowland swamps support an unattractive vegetation composed chiefly of rushes 
and similar plants, with some stunted flax [Phormium tenax) and maimka or tea-tree (Leplo- 
spermum scoparium), which, like the flax, is dwarfed and miserable-looking. Along swamp- 
borders, or where the ground is poorly drained, kahikatea is the principal tree, and mingimingi 
or black scrub forms the usual undergrowth. 

(3.) The Rata and Beech Zone. — Above 1,500 ft. there is a distinct change in the forest 
growth. The trees become smaller, and the undergrowth scantier, whilst bush-lawyers, supple- 
jacks, and other creepers nearly disappear. Tree-ferns are no longer seen, and the smaller 
ferns are less abundant. There is, however, an abundance of lycopodiums and mosses. 
There are not so many varieties of forest-trees as in the zone below, and there is a tendency 
for one or two kinds of tree to occupy considerable areas. The most common tree is now 
the southern rata [Melrosideros lucida), with the beeches, or so-called birches [Xothofayu.s 
menziesii and A', solandri), ranking next in abundance. Broadleaf (Griselinia littoralis) 
flourishes on the flatter and damper portions of the ridges. Another common tree is the 
kawhaka, or cedar {Libocedrus hidwillii). The handsome mountain-cabbage, or toi [Cordyline 
indivisa) is of frequent occurrence in this zone. A coarse grass often grows in the forest glades. 
As a height of 3,000 ft. is aproached, the forest becomes more and more stunted, and species 
more characteristic of the next zone make their appearance, such as the mountain-flax 
[Phormium, cookianum), neinei [Dracophyllum Iraversii), &c. 

(4.) The Subalpine Zone. — At about 3,000 ft. a rapid well-marked change takes place 
in the forest. An almost entirely new series of small trees and shrubs makes its appearance. 
The most noticeable of these are various Olearias, usually with moss-covered trunks and 
branches ; snow-tree or neinei [Dracophyllum Iraversii) ; needlewood (Z>. lonyifolium) ; moun- 



10 

tain-pine {Dacrydium intermedium): mount liii-ribboiiwood (Gaya lyallii) ; and a small rata 
(probably Metrosideros parkinsoni). 

Where the soil is derived from underlying mica-schist the alpine scrub grows so thick 
and matted that it is nearly impossible to force one's way through it. This is especially the case 
when akeake is abundant, the various species of Olearia included under this name having 
at this altitude extremely twisted and gnarled interlacing branches. In order to make a track 
through the mountain scrub much cutting is required, but once made the track remains in fair 
order for many years. 

Wherever the mountain-slopes consist of granite or siliceous gneiss a poorer soil results, 
and there is a smaller variety of plant-life. The alpine scrub is consequently less dense than 
in the schist country, and a comparatively easy passage can often be made through it to 
the alpine meadowland above. 

In those localities where serpentine or talcose schist outcrops, the soil is unfavourable 
to the growth of most of the subalpine shrubs, and the scrub consists principally of mountain- 
pine, needlewood, neinei, and a small species of Metrosideros, whilst numerous open glades 
appear, with a growth of tussock and other coarse grasses. 

The higher limit of the subalpine zone depends largely on the configuration of the ground. 
On level ground or gentle slopes the scrub may almost cease at 3,000 ft., whilst tussock 
(Danthonia raoulii) and characteristic alpine plants appear in abundance ; but the scrub gene- 
rally continues to about 3,600 ft., at which altitude it is only two or three feet high. On steep 
slopes it may persist to elevations of 4,500 ft., gradually becoming more and more stunted as 
the height increases. Almost the only shrub there seen is a species of Dracophyllum, either 
identical with or closely allied to the needlewood (Z>. longifolium) ; but its small leaves and 
stunted habit make it appear quite a different plant from the shnib typical of lower eleva- 
tions. 

(5.) The Alfine Meadowland. — The remarkable Hora which flourishes on the mountains 
of New Zealand above the timber-line has received a great deal of attention from botanists. 
Its wonderful flowers, and the many curious plants specially adapted for the conditions under 
which they grow, have been more or less described by many writers. 

In the Mikonui Subdivision the plant assemblage of the alpine meadowland is similar 
to that in other parts of New Zealand ; but, since the mountain-areas have never been ex- 
amined by a botanist, it is not unlikely that plants new to science may there exist. 

The most noticeable flowering-plants are the splendid mountain-lily (Ranunculus lyallii) : 
its near ally the large yellow buttercup {li. cjodleyanus) ; the mountain-daisy, or cotton-plant 
(Celmisia coriacea). with flower-heads 3 in. or more in diameter: white-flowering gentians 
(Gentiana coryvibosa and other species) ; a violet (probably Viola cunninghamii) ; and edelweiss 
(Helichrysum hellidiodes and H. grandiceps) ; but there are many other fine flowers belonging 
chiefly to species of Ranunculus, Senecio, Celmisia, and Gentiana. The mountain-carrot 
(probably Ligusticum haastii) and aniseed {Angelica gingidium) are often abundant. The 
former plant is much relished by sheep and cattle. At least two species of " Spaniards," or 
speargrass (Aciphylla), are of frequent occurrence. Another common plant, usually seen just 
above the bush-line, is the mountain-tutu {(Joriaria angustissima). This plant, with its herba- 
ceous branches and extremely numerous small leaves, is in these respects quite different from 
the common tutu, but the flowers and fruit are very similar. 

Among the grasses, a large tussock (probably Danthonia raoulii) and the carpet or 
hassock grass {D. au^tralis) are very common. In some districts, more especially in the Upper 
Wanganui watershed, toetoe-grass, apparently the same species as that so common in the 
lowlands (Arundo conspicua), grows in great abundance, almost to the exclusion of tussock 
and other grasses. 

Above 6,000 ft. the mountain slopes and tops are for the most part covered either with 
broken rocks or pei-petual snow, but here and there, up to perhaps 7,000 ft., a little hassock-grass 
and a few of the characteristic alpine plants are occasionally seen. A few patches of lichens 



11 

occur upon tlio rocks, whilst the not infrequent occurrence of masses of pink snow indicate the 
presence in the snow of an alga, the same as or allied to the Sphcurdla nivalis of the European 
Alps. 

Character of JiAnd and Soil. 

The laud in the Mikoiuii Subdivision varies much iji (|iiality, but when cleared and, 
if necessary, drained will almost all grow good pasture. At the present tinu', however, only 
the best of the land will pay for the expense of clearing, grassing, and otherwise improving ; 
but the time \sill probably come when the greater part of the lowlands will be brought under 
grass, and Westland will become pre-emijiently a dairying district. 

From an agricultural point of view Westland land may be divided into the followng 
six classes : — 

(1.) The modern coastal plain. 

(2.) Flood-plains of the lower river valleys. 

(3.) Lowland river terraces, morainic deposits, fans, &c. 

(4.) Mountain-slopes up to the bush-line. 

(5.) GrazLng-land above the bush-line. 

(6.) Mountain peaks and ridges above the grass-line. 

(1.) The Modern L'oaMal Plain. — In the Mikonui Subdivision only a small area comes 
under this head, and the greater part even of this still remains in its natural condition of bush 
•iud swamp. Near Ross and the mouth of the Mikonui the small areas which have been 
cleared and grassed make excellent grazing-iands. 

(2.) Flood- plains of the Lower River-valleys. — The best land in the subdivision is com- 
prised under this heading. The soil is generally a tine silt from 1 ft. to 6 ft. or more in depth, 
resting on river-gravels, and consequently well drained. It is composed.mainly^'of material 
from the mica-schist mountarns, deposited during flood-times. When cleared, this land 
as a rule grows splendid grass and root crops, but is rather light for cereals. 

Experiments made by the .Agricultural Department* have shown that the addition of 
lime not only greatly im^reases the gro\vth of grass, satisfactory though this generallv is, but 
aifio makes the land capable of bearing good graui-crops. 

The open patches of land near the river-banks and the grassy islands have generally a poor 
stoj\v soil, but, owing to their well-drained character, form excellent grazing country for (tattle, 
and more especially for sheep. 

A considerable portion of the flood-plains consists of open swamp, which can be drained, 
but only at considerable expense. In years to come the swampv areas will almost certainlv 
be utilised for growing New Zealand flax (Phurmium tenax), for which purpose, if partly 
drained, they are admirably suited. 

(.3.) Lowland lliver-lerraces, Morainic Deposits, Fans, &c. — Probably three-fourths of 
the lowlands come under this heading. There is a heavy growth of timber on all this laiid. 
The soil-covering is generally rather thin, and in quality varies from somewhat poor to fair. 
As the milling-timber is cut out, it will be found profitable to complete the clearijigs in most 
localities ; but in some parts there is a layer of clayey subsoil, which hinders drainage. In 
consequence, the soil is sour, and cannot be made to grow grass without expensive drainage 
operations. 

The purely morainic deposits generally have a very uneven surface, but the fluvio-glacial 
and river-terraces form a great deal of nearly level land. Many of the creek-fajfs at the foot 
of the mountains are composed of fine grave's, and are well adapted, after being cleared, for 
grazing purposes. Some of the talus slopes are of similar character, being really to a great 
extent coalescing fans formed by numerous small streams, rather than pure talus. 



♦ B. C. Aston: " Wire-basket Method of Testing Soils," Bulletin No. 2, Chemistry Division, N.Z. Dept. 
of .\gricultiire, 1907. Further information will be found in the '" Report of the Department of Agriculture " 
for this year (1908). 



12 

(4.) Bush-dad Mountain-slopes. — Where the mountains are composed of mica-schist, a 
fertile, though often thin, covering of soil results, capable of growing good pasture. Flat 
spurs and gentle slopes might perhaps be cleared with advantage, but the general clearing of 
the hillsides would be an miwise pohcy, both because the soil would soon be washed away by 
the heavy rains, and because disastrous floods would result when the run off of the rainfall 
was no longer checked by forest growth. 

Where gneissic schist or granite forms the imderlyiug rock, the soil is poor, and the forest 
vegetation less vigorous than elsewhere. 

(5.) Grazinrj-land above the Bush-line. — This division is the alpine meadowland of the 
botanist, and contains a large area of land which during summer and early autumn is suitable 
for grazing the hardier varieties of sheep. More especially where the mountain-carrot (Ligusti- 
cum haastii) is plentiful, sheep thrive and fatten. Notwithstanding its apparently excellent 
possibilities, the attempts hitherto made to utilise the alpine meadowland for sheep-grazing 
have not proved profitable, because, in the first place, the land can be used onlv during summer 
and early autumn, when feed is generally plentiful in the lowland clearings ; and, secondlv. 
because the losses from one cause or another are very heavy. It is possible that, by clearing 
and grassing limited areas of the adjacent moiuitain-slopes where the sheep could winter, 
the alpine grass-land might be profitably stocked ; but, as already noted, there are serious 
objections, besides the matter of expense, to such a course. Moreover, the non-utilisation 
of the mountain grazing-land is not altogether an e\al. The botanist and the lover of nature, 
at any rate, mil rejoice in the certainty of the alpine flora of Westland remaining unaffected 
by the pasturage of animals for many years to come. 

(6.) Mountain Peaks and Ridges above the Grass-line. — From an agricultural point of 
view little need be said under this head. Even where not covered by perpetual snow, the 
surface of solid or broken rock is practically destitute of soil and vegetation. 

Climate. 

The climate of the Mikonui Subdivision is practically the same as that of the area immedi- 
ately to the north described in Bulletin No. 1.* Its outstanding feature is the hea\y rain- 
fall ; but there are many days during the year when ideal weather prevails, especially on the 
lowlands near the sea-coast. The summer heat is never excessive, and the winter frosts are 
seldom severe in the low cou itry. Gales are less frequent than in most other parts of New 
Zealand. Snow practically never falls near the sea-coast ; but as one proceeds inland, and the 
elevation increases, more and more of the winter precipitation is in this form. On the higher 
parts of the mountains snow may fall in any mouth of the year, but during the summer months 
very little does fall as a rule ; for instance, during the three months December, January, 
and February of the 1906-7 season only one snowfall was observed (on the 18th January, 
1907). On this occasion snow fell during the afternoon around the hut near Frew Saddle, at 
an elevation of about 2,000 ft., and lay on the ground till the following morning. During the 
corresponduig months of 1907-8 we did not observe snowfalls of any kind on the mountains 
in the Waitaha and Wangaiiui watersheds. 

In connection with the subject of water-power, the amount and frequency of the aqueous 
precipitation are matters of importance. 

Unfortunately, no meteorological records of any value have ever been made in the Mikonui 
Subdivision, but rainfall records from Hokitika, Greymouth, Otira, and Okuru are available. 
These are gk'en in the subjoined tables, together with the Westport and Reefton statistics. 
From these figures it is evident that the rainfall on the West Coast increases from north to 
south, and the Otira returns prove, as might be expected, that the rainfall inland is much 
heavier than on the sea-coast. It may therefore be inferred that the rainfall even on the coast 

* Bell, J. M., and Eraser, C. : " The Geology of the Hokitika Sheet, North Westland," BuU. No. 1 (New 
Series), N.Z.G.S., 1906, pp. 15-17. 



13 

of the subdivision is somewhat greater than that of Hokitika, and that as one proceeds inland 
the precipitation increases, and from the foot of the main mountain-range to near the main 
divide is at least equal to that recorded at Otira. 

The writer's own observations more than confirm these deductions. While field-work 
was in progress a record was kept of weather-conditions, and heavy rainfalls were frequently 
roughly measured by exposing suitable vessels, and measuring the depth of rain-water which 
accumulated in them. The heaviest rainfall experienced was on the 7th, 8th, and 9th March, 
1907, when the geological survey-party was camped at the junction of the Hokitika and Whit- 
corabe rivers (about twenty miles from Hokitika in a straight line). During these three days 
the measured precipitation was 24 in. At Hokitika a rainfall of 7"61 in. was recorded during 
the twenty-four hours ending 9 a.m. on the 9th. 

A rough idea of the ramfall of any district can be obtained by measuring the flow of the 
streams, and comparing this with the drainage-area. The stream-measurements made during 
the course of the survey "of the Mikonui area indicate, after all possible arllowances are made, 
an annual precipitation of not less than 200 inches over the mountainous area, and, indeed, 
there is reason for believing that it may. exceed 250 inches per annum. The only exception 
is furnished by the Totara, a snuill stream with much of its watershed near the coast. The 
observations made by members of the ( Geological Survey parties seem to show that the maxi- 
mum precipitation takes place on the outer portions of the alpine chain, over a belt of about 
eight or ten miles wide. Towards the main divide the rainfall is on some occasions at least, 
perceptibly less, and a mile or two on the Canterbury side much less than in the belt of maxi- 
mum rainfall. According to the obser\'ations of Mr. A. P. Harper this is not the case in the 
Mount Cook district. He states that the precipitation there is almost, if not quite, as great 
for some miles on the eastern side of the Alps as on the west.* Here, however, the western 
flank of the alpine chain is narrower, and the main divide, though higher, is considerably 
nearer the west coast — considerations which may f.xplain the heavy precipitation on the 
eastern flanks. 

The average annual rainfall at Westport is 7709 in. ; at Greyniouth, for a period 
of fifteen years, it is 10413 in. ; whilst at Hokitika, for two periods, the earlier of fifteen 
years and the later of thirteen years, it is 117-."}5in. At Ileefton the average rainfall is 
})iobably about 80 in. ; at Otira the average for two years (one incomplete) is 18212 in. ; 
whilst at Okuni the rainfall for 1906 was 17282 in., and for ten months of 1907 it was 
150-38 in. 

At Bealey, which is only fifteen miles by road from Otira, and about ten miles from Arthur's 
Pass, the average annual rainfall is only 5819 in., and the number of rainy days 120. 
Since Bealey is bm six or seven miles at mo.st in a direct line from the main divide, the reduc- 
tion in precipitation is very marked. 

At the Mount Took Hermitage, however, which is some miles on the east side of the main 
divide, the annual rainfall, so far as the observations go is probably greater than that at 
Okuru, the nearest meteorological station on the West Coast. 

The table on the ne.xt page, which has been kindly supplied by the Meteorological Bran(;h 
of the Marine Department, shows the rainfall and number of rainy days at Hokitika, Westport, 
Greymouth, Okuru, Otira, and Reefton during the years 1905-6-7. Following this, on i)age 15, 
is a table showing recorded rainfalls at these stations and also at Bealey and the Mount Cook 
Hermitage duriiig the first three months of 1908, together with a tal)le showing weather expe- 
rienced during the time the writers party has been in the field. During five or six months 
of this period the observations were recorded in the immediately adjoining Hokitika Sub- 
division. Days on which rain did not fall during the hours of daylight are not considered 
as rainy days. 



♦ " Pioneer Work in the Alps of New Zealand," 1896. p. 317. 



14 



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15 



Table 2. — Rainfall during the First Three Months of 1908. 





January. 


' '.February. , 


March. 


Total. 


1 


Inches. Days. 


Inches, i Days. 


Inches. 


Days. 


Inches. 


Days. 


Westport . . 


1-55 


7 


203 


7 


9-28 


16 


12-86 


30 


Reefton (643 ft.) 




1-50 


6 


1-05 


i> 


6-37 


18 


8-92 


29 


Greymouth . . 




2-48 


9 


3-59 


6 


15-23 


13 


21-30 


28 


Otira (1.255 ft.) 




4-05 


6 


8-45 


7 


24-49 


14 


36-99 


27 


Okuru 




6-61 


8 


9-93 


8 


20-67 


12 


37-21 


28 


Hokitika . . 




2-65 


6 


5-08 


o 


14-56 


13 


22-29 


24 


Bealey (2,130 ft.) . . 




112 


4 


3-20 


4 


7-39 


14 


11-71 


22 


Hermitage (2,510 ft.) 




8-92 


8 


12-24 


4 


29-51 


14 


50-67 


26 



Table 3. — Rainy Days dubino Course of Geological Suevby as recorded in Camp. 




' Incomplete months. 



During the part of 1905 devoted to field-work there were 76 fine days ; whilst in 1906, 
1907, and 1908 there were 156, 112, and 86 fine days respectively during the periods in which 
field-work was carried on : or, in all, there were 430 fine days to 404 wet days. Had days on 
which slight showers fell, or those followed by wet nights, been included with rainy days the 
number of the latter would have been considerablv increased. 



Scenery? 

The greater part of the wild and beautiful scenery of the Mikonui Subdivi.sion is in- 
visible to the ordinary traveller, who, as he follows the coach-road from the Totara River 
southward, obtains but occasional glimpses of the snow-clad peaks of the Southern Alps. Here 
and there, however, more gentle landscapes may be seen. The farms in the Lower Totara 
and Mikonui valleys, the clearings at Ferguson's and near the Wanganui River, afford pleasing 
spots of lighter green, which contrast agreeably with the darker background of the forest. 

For many miles the road runs through the splendid bush for which Westland is famous, 
and without leaving the beaten track one may see most of its charms. The stately rimu, 
with its graceful branches is alike the most useful and the most beautiful of the forest-trees ; 
but there are many others almost its peers. At different periods of the year the white-flowering 
clematis and the crimson blooms of the rata charm the wayfarer. Even more attractive are the 
tree-ferns, which everywhere outspread their curving fronds. Many other beautiful ferns adorn 
the forest glades, and a wealth of festooning creepers may be seen on every side. This 
abundance of tree-ferns and lianes gives the forest an almost tropical aspect, and suggests that 
much of our New Zealand plant-life has come from a warmer region — a lost continent, it may 
be, that once extended far to the north. 

Along the sandy beach stretching south of the Totara River, scenically the most interest- 
ing feature is furnished by the open sea, which during westerly gales rolls in great billows 
upon the shelving beach. The morainic Bold Head presents a vertical face to the waves, 
fringed bv enormous boulders derived from the glacial drift : whilst towards the Wanganui 
River an even more remarkable morainic cliff faces the ocean for manv miles. 



16 

lanthe, eighteen miles south-west of Ross, the only lake of any size in the district, though 
yielding the palm to Kanieri, is a beautiful sheet of water, with bush-clad shores, from the 
surface of which a fine view of the alpine chain is obtained. The lake is easy of access, the 
Main South Road passing along its eastern shore. 

In their lower reaches the rivers present no views of extraordinary interest, but from the 
points where they enter the mountain-ranges they exhibit charming scenes of ever-varying 
magnificence. Now they flow in wide valleys with bush-clad slopes and distant views of snowy 
peaks ; anon they plunge into deep rock-bound gorges, confining them to narrow channels 
encumbered with huge boulders, over which the water dashes in waldly magnificent rage. The 
smaller tributary streams descend the mountain-sides in waterfalls, in places of great height, 
or in foaming cascades, varied by gentler reaches. 

As one ascends towards the sources of the main rivers the mountain scenery becomes 
more and more impressive. Frowning precipices, the height of which may often be measured 
by thousands of feet, appear close at hand. Jagged ranges, fantastically shaped rock-faces 
interspersed with patches of snow, soaring cloud-kissed peaks, vast snowfields, beautiful 
cliff and valley glaciers, alpine meadowlands, the tender if often sombre shades of the bush, 
make a dazzling ensemble which cannot be described, and baffles the artist's skill to depict. 



Literature. 
The abbreviations used are — 

Trans. : Transactions of the New Zealand Institute. 

Rep. G.S. : Reports of the Geological Survey of New Zealand. 

Mines Report : Papers and Reports referring to Minerals and Mining (the annual 

volume published by the New Zealand Mines Department). 
A capital letter followed by a figure (thus, C.-3) refers to a New Zealand parlia- 
mentary paper. 
1867. Hochstetter, Ferdinand von : " New Zealand." (English translation.) 

On pp. 115-117 is a description of the West Coast Goldfields. ' Chap, xxi 
(pp. 478-511) describes the Southern Alps. 
1867. Hector, James : " Abstract Report on Progress of the Geological Survey of New Zea- 
land during 1866-67." 

In this summary report (p. 13) Sir James Hector makes a reference to the Ross 
diggings. 
1869. Hector, James : " On Mining in New Zealand." Trans, vol. ii, p. 361. 
On pp. 369 and 370 are references to the deep leads at Ross. 

1876. " Eleventh Ammal Report on the Colonial Museum and Laboratory." 

On pp. 22-24 is a lengthy reference to the Rangitoto Silver Mine. 

1877. Hector, James : Rep. G.S. during 1874-76, vol. ix. 

In his progress report (p. xii) Sir James Hector refers to assay results of ore 
from the Rangitoto Silver Mine. 

1877. Cox, S. H. : " Report on Westland District." Rep. G.S. during 1874-76, vol. ix, 

pp. 63-95. 

In this valuable though brief report Cox deals generally with the geology of 
Westland. On pp. 76 and 87-89 he refers to Mount Greenland, near Ross, and the 
Rangitoto Silver Mine. 

1878. " Twelfth Annual Report on the Colonial Museum and Laboratory." 

On pp. 32, 33 are further references to the Rangitoto Silver Mine. 

1879. Hector, James : Rep. G.S. during 1878-79, vol. xii. 

In his progress report Sir James Hector refers to the Rangitoto Mine (p. 17), 
and to rock-specimens collected in the Upper Hokitika Valley (p. 18). 




!=- 0, ;5 




•^ 



5 X 



y, — 

o _ 



17 

1879. Voii Haast, Julius : "The Geology of Canteibuiy and Westland.*' 

In this admirably written volume Von Haast has a good deal to say in reference 
to the geology of the Mikonui Subdivision. In particular he describes the gneiss- 
granite formation at the Hokitika River gorge, and the huge morainic deposits near 
the Wanganui River. He makes reference also to the neighbourhood of Ross and 
Mount Rangitoto. 
1883. Hector, James : Rep. G.S. during 1882, vol. xv. 

In his progress report Sir James Hector refers on p. 15 to ground-sluicing at 
Ross. 

1883. (!ox, S. H. : " On Certain Alluvial Gold- workings in We.stland." Rep. G.S. during 

1882, vol. XV. 

Pp. 52, 53 refer to the Ro.ss Gold-mining Company. The report contains an 
interesting map showing the claims, .surface and underground levels, positions 
and inclinations of the auriferous layers, &c. 

1884. Cox, S. H. : " Sluicing Claims in Westland." Rep. G.S. during 1883-84, vol. xvi. 

The sluicing claim of the Ross United Gold-mining Company is briefly described 
in this report (pp. 89, 90). 

1886. Reid, R. C. : " Rambles on the Golden Coast." 

This book is chiefly descriptive of the early history of the West Coast and of its 
tine scenery. A chapter is devoted to an account of a visit to the Rangitoto Silver 
Mine. 

1887. " Handbook of New Zealand Mines." 

This publication, compiled by Mr. P. Galvin, under the direction of the Hon. 
W. J. M. Larnach, then Minister of Mines, gives a complete account of mining in 
New Zealand at the time of its issue. It contains much interesting matter relating 
to the early explorations and gold-discoveries on the West Coast. 

1891. McKav, Alex. : " On the Geology of Marlborough and South-cast Nelson." Part ii, G.S. 

Rep. during 1890-91. 

On pages 2. 3, 7, and elsewhere are references to the structure of the Southern Alps., 
and incidentally to the neighbourhood of Ross. 

1892. ■' Index to Fossiliferous Localities according to the Counties in which they occur." 

Rep. G.S. during 1890-91, vol. xxi. 

On p. 177 reference is made to Tertiary rocks and fossils in the neighbourhood 
of Ross. 

1892. McKay, Alex. : " On that Part of the West Coast Goldfields lying between the Tere- 

makau and Mikonui Rivers, Westland." Bulletin No. I [Old Serie-s] of New 
Zealand Geological Survey. 

References are made in this little pamphlet to the auriferous gravels of Ross. 

1893. McKav, Alex. : "' (Geological Explorations of the Northern Part of Westland." Mines 

Report, 1893, C.-3, pp. 132-I8H. 

This is a full and valuable report, describing the general geology, auriferous 
leads, &c., of the area between the Grey and the Mikonui rivers. It contains a 
summary of previous literature relating to Westland, and is accompanied by a coloured 
map. Mr. McKay has much to say concerning the origin of the alluvial gold de- 
posits. He considers that the gold was largely derived in the first place from a 
mountainous area lying to the west, which has now disappeared beneath the sea, 
and that a primary concentration of the alluvial gold was brought about by an ancient 
river, which ran from near Ross to Tasman Bav. Further leferences to McKay's views 
will be made in the body of this report. 

1894. McKay, Alex. : " On the Kumara Gold-drifts, Westland." Rep. G.S., 1892-93, vol. xxii. 

pp. 6-11. 

In this short report are references to the auriferous gravels at Ross. 
2 — Mikonui. 



18 

1894. McKay, Alex. : " On the Geology of the Northern Part of Westland, and the Gold- 

bearing Drifts between the Teremakau and Mikonui Rivers." Rep. G.S. 1892-3, 
vol. xxii, pp. 11-50. 

This report covers much the same ground as that published the previous year 
in the Mines Report. 

1895. McKay, Alex. : " Report on the Geology of the South-west Part of Nelson and the 

Northern Part of Westland." Mines Report, 1895, C.-13. 

This report contains many references to the auriferous gravels and geology of the 
Ross district. 

1896. Gordon, H. A., and McKay, Alex. : " Mining Reserves, Nelson and Westland." Mines 

Report, 1896, C.-9. 

This report deals with several areas in the Mikonui Subdivision. In the 
discussion on the origin of the auriferous gravels, McKay's views as expressed in 
his reports of 1893 and 1894 are repeated. 

1897. Gordon. H. A. : Presidential Address, Trans. N.Z. Institute of Mining Engineers, vol. i. 

On pp. 13 and 14 are references to Westland geology and the deep leads at 
Ross. 
1899. McKay, Alex. : " Notes on the Auriferous Ironsands of New Zealand." Mines Report, 
1899, C.-9, pp. 15, 16. 

Mention is made of the auriferous black-sands occurring on the sea-beaches 
of the Mikonui Subdi\'ision and other parts of Westland. 
1901. McKay, Alex. : " Geological Explorations." Mines Report, 1901, C.-IO. 

On pp. 2 and 3 are references to coal on Koiterangi Hill and in Coal Creek, 
Ross. 
1901. McKay, Alex. : " Report of Coal in Koiterangi (Camelback Hill), Kokatahi Plain, 

Westland." Mines Report, 1901, C.-IO, pp. 8, 9. 
1901. McKay, Alex. : " Report on Indications of Coal in Coal Creek, Ross, Westland." Mines 
Report, 1901, C.-IO, pp. 9, 10. 

1903. McKay, Alex. : " Gold-deposits of New Zealand." 

In this Uttle work, which is reprinted from the New Zealand Mines Record, 
McKay, in describing the auriferous deposits of the West Coast, makes special re- 
ference to those near Ross. 

1904. Hay, P. S. : " New Zealand Water-powers." 

Pp. 18-20 give an account of available water-power in Westland. 

1905. Marshall, P. : " Geography of New Zealand." 

In this work various references are made to the physical features, rainfall, &c., 
of Westland. 

1906. Bell, J. M., and Fraser, C. : " The Geology of the Hokitika Sheet, North Westland 

Quadrangle." N.Z. G.S. Bulletin No. 1 (New Series). 

This report, dealing as it does ^\^th the adjoining area, throws much light on the 
geology of the Mikonui Subdivision. (On future pages the title of this report will be 
abbreviated to " Bull. No. 1 (New Series) N.Z.G.S.") 
1906. " The New Zealand Mining Handbook." 

This publication, on much the same lines as the 1887 Handbook, was edited 
by Mr. P. Galvin, and issued under the authority of the Hon. James McGowan, 
Minister of Mines. 
1906. Sollas, W. J., and McKay, Alex. : " Rocks of the Cape Colville Peninsula," vol. ii. 

This volume contains petrographical descriptions by Professor Sollas, with 
excellent micro -photographs and additional notes by Mr. McKay respecting a number 
of Westland rocks, one or two of which are from the Mikoimi Subdivision. 
1906. Gordon, H. A. : - Mining and Engineering and Miners' Guide." Third Edition. 
On pp. 78 and 79 are references to Rois Flat. 



19 

Besides the literature quoted, a considerable number of references to Westland geology 
wall be found in the numerous papers by Sir JuUus von Haast, published in the " Transactions 
of the New" Zealand Institute," and in various foreign journals. Several of this writer's 
earlier reports, published by the Canterburj' Provincial Grovenmient, contain much informa- 
tion relating to Westland, but practically the whole of this is repeated or summarised in " The 
Geology of Canterbury and Westland." 

The annual reports of the Mines Department (" Papers and Reports relating to Minerals 
and Mining ") from 1887 to the present time contain many scattered notes referring to 
mining ui the Mikonui Subdivision ; whilst the ^ew Zealand Mines Record from 1897 
onwards also contains frequent references to the mining industry in this area. 



2* — Mikonui. 



20 



CHAPTER II. 



CULTURE. 



Inhabitants 

MeanH of Communication 

Alluvial Mining Industry 

General and Historical Account of Allu- 
vial Mining . . • • 
Methods of working Alluvial Claims and 
Gold-saving Appliances 
Auriferous-quartz Minine 
Silver-mining . . 



Paee 
20 Coal- mining. . 

20 Special ilining Areas 

22 Water-races 

Gold-production 
22 Timber Industry 

Agricultural and Grazing Industries 

24 Dairying . . 

25 Honev 

26 Flax " 



Pase 
26 
26 
28 
28 
28 
29 
29 
29 
29 



Inhabitants. 
The greater part of the Mikonui Subdi^^sion is unsettled, and much of the remainder, ow-ing 
to its rugged character, will probably ever remain without permanent inhabitants. At the 
present time the total population of the area is about eight hundred. Ross, the only town- 
ship, is twenty-one miles by road from Hokitika, and was at one time a busy mining camp, 
with several thousand inhabitants ; but for many years the mining industrj' of the district 
has been decadent, and the population, according to the census of 1906, was only 576. The 
Uttle town has been a municipality since its early days, and possesses well-formed streets 
and a good water-supply. In addition to a post and telegraph office, the to■u^^ has a telephone 
bureau, and possesses direct telephonic communication not only -n-ith Hokitika and other 
places to the north, but also with the various settlements southward as far as Okarito. 
Ross owes its existence principally to the occurrence of richly auriferous gravels in its neigh- 
bourhood. Though the upper water-free portions of the golden beds have long been worked 
out, it is hoped that the deep levels, now being reopened, will bring renewed prosperity and 
increased population. For many years past the Mont d'Or Sluicing Claim has been the main- 
stay of the place, and is still yielding highly payable returns. 

In the immediate vicinity of Ross are a few alluiaal miners and dredgemen, as well as a 
number of settlers who farm the flat land of the coastal plain and the lower valleys of the 
Totara and Mikonui rivers. That part of the Koiterangi-Kokatahi Plain which lies within 
the subdivision has four or five permanent settlers, as well as several landholders who are 
occasional residents. 

The principal farming settlement of the subdivision is in the Waitaha Valley, where some 
5,000 or 6,000 acres of river-flat are occupied by settlers, who are making good progress 
in the work of replacing the bush by grass paddocks. On the north side of the Wanganui 
River a number of sections have been taken up, and there are now several permanent residents. 
Two or three isolated settlers, together %vith one or two " black-sanders " along the sea-beach 
and a few buskmen, complete the population list of the area. The southern part of the 
Wanganui Plain, which, though outside the subdi\4sion, has been included in the maps, 
supports a small but prosperous farming community. 



Means of Communication. 

The Mikonui Subdi\'ision has no seaport, and therefore its inhabitants depend on Hokitika 
and Greymouth for their means of communication with the outside world. The Greymouth- 
Hokitika railway-line has been extended southward as far as Ruatapu, near Lake Mahinapua, 
and the formation is at the time of writing completed to Ross, so that within a few months 
railway-communication with the north will be established. 



PLATE VI. 




ViKW UK PiiiCK Flat (Whitcomhk Vai.i.kyj, .shuai.m. llANt.i>.(. Vallkv AiNU Kai.i.s uf Pkice 

HiVKH TO THE UKillT. MoUNT VoN UkDISN IN CKNTHAL BACKGKOUXD. 




WlUK Koi'K AMJ C'acE OVIOl! lloKITIKA RlVKli AliOVL Wll 1 1 COM Hi; JUNCTION. 



Gtol. Hull. So. 0.] 



[Tu fare iJU'je M. 



I'J.ATK VII. 




View j'hom Mathias Pa^s (I.GIO ft. ), looking West into Vallkt of Upper Hokitika. 




View fhom Mathias Pass lookim; dowx Caxyox Ckeek (Caxtekbuky Side). 
Gtvl. Bull. Xo. 6.1 [To fart i,u<jc 21. 



21 

At the present time the principal artery of traffic is the Main South Road, which enters the 
subdi\'ision by a bridge over the Totara River three miles from Ross, and runs in a genercil 
south-westerly direction through the area, finally reaching the Wanganui River, where it 
passes out of the subdivision. Along the road are three post and telephone offices — one on 
the west side of the Mikonui ; another at Ferguson's, nine or ten miles from Ross ; and the 
third at Urquhart's, about six miles further on. There is also a post and telephone office 
at Hende's, on the south side of the Wanganui River, just outside the subdivision. 

There is a daily mail-coach northward from Ross running on alternate days to Ruatapu 
and Hokitika. Coaches run southward twice a week, one going to the Wanganui River only, 
the other to the Waiho River, forty or fifty miles further on. 

The only river bridged on the Main South Road beyond Ross is the Waitaha, so that traffic 
is frequently interrupted by floods. There are, however, foot-bridges over the Mikonui and 
Kakapotahi rivers, and a ferry-boat at the Wanganui River. 

There is a good road from Hokitika southwards to Kokatahi and Koiterangi, which enters 
the subdivision near Koiterangi Hill, and continues as far as the first gorge of the Hokitika 
River. Thence a bridle-track has been made for six miles, bringing one to the junction of the 
Hokitika and Whitcombe rivers. From this point there is only a foot-track. Half a mile 
above the j auction the Hokitika River is crossed by means of a wire rope and cage, and the 
track, doubling back to the Whitcombe, follows up the eastern side of its valley for about 
ten miles, where it practically ends. From here to Whitcombe Pass, a distance of six miles, 
the river-bed is followed by the occasional traveller or prospector. The track, so far as formed, 
is on the whole in serviceable condition at the present time, though there are some bad places. 

A shorter route to tlie main divide is afforded by a foot-track, which, branching off near 
Frew CVeek from the Whitcombe Pass trail, leads to Frew Saddle, whence, by following the 
valley occupied by the headwaters of the Hokitika, Mathias Pass is reached. 

Several shelter-huts, all in fairly good order, have been built along these tracks. The 
positions of these are indicated on the maps of the Toaroha and Murray survey districts. 

During the season 1906-7 a rough foot-track was constructed by the topographical party 
under Mr. Greville from the cage over the Hokitika River up the right (northern) bank to th 
Mungo junction. Thence it was continued up the Mungo for some distance till more open 
river-bed was encountered. By this route Mungo Saddle, a somewhat lofty col on the main 
divide, can be reached. 

There is an old, somewhat o\ergrown track up the left or western bank of the Hokitika 
and Whitcombe rivers from the first gorge near Diedrich's station to some distance above 
the Cropp River, which in many places simply follows the river-bed. This was cleaned out 
and made serviceable for a time by the Geological Survey parties. 

Near Diedrich Creek a branch from the road to Hokitika Gorge goes o£E to the north-east 
for about two miles, and is continued as a bridle-track behind Doughboy Hill, ultimately 
ending near Lake Arthur. A branch from this track leads to the Hax-mill near the Kokatahi 

River. 

A road, which for several miles is used for wheeled traffic, follows the west side of the 
Totara River Valley. It continues as a graded horse-track for many miles, ultimately crossing 
the low saddle near the head of the Totara into the Upper Mikonui Valley. Formerly it 
ended about a mile before Mr. P. Gribben's cottage is reached, but has lately been continued 
over a bluff on the north side of the Mikonui to within a short distance of this homestead. 
A branch from this track about two miles in length leads to Zala's battery, a small deserted 
mining plant near the head of Farmer Creek 

From Ross a horse-track leads to the bare sujnmit of Mount Greenland, whilst a branch 
from it made along the western slope of the mountain takes one to Veronica, a deserted 
mining camp at the head of Cedar Creek, which cui also be reached by a short foot-track from 
the top of Mount Greenland. There are shelter-huts erected by the Government both on 
Mount Greenland and at Veronica. 




MUSEUM 



22 

li'rom the main road on the south side of the Mikouui a branch road runs towards Bold 
Head, but has not been completed for much more than a mile. From the end of the road a tram- 
line has been constructed to a small sawmill near Bold Head, a further distance of over two miles. 

On the south side of the Kakapotahi River an excellently graded horse-track leads from 
the main road into the flat upper valley of that stream, known as Happy Valley. A branch 
from this track has been made to the old Rangitoto Mine, and is still in fair order nearly all 
the way. There is also an old foot-track to Rangitoto, now overgrown, which starts from 
the main road about three miles south of the Mikonui River ford. 

An excellent road branching off from the Main South Road has been made for seven or 
eight miles up the Waitaha Valley, thus giving access to the Waitaha Settlement. It ends 
on the river-bank not far from the low isolated hill called the Waitaha Sugarloaf. 

The only other track of any consequence in the subdivision is one starting from the main road 
on the south side of Duffer Creek, and leading to the sea-beach near the mouth of that stream. 

As already mentioned, many miles of rough track were cut or blazed by the Geological 
Survey parties, and there are several similar tracks in fair order which were made by the 
Lands and Survey Department, but these need not be further specified.* 

The sea-beach of the subdivision forms an excellent natural road for horse traffic, which 
was followed in the early days by the first explorers and gold-diggers. The bluffs at Bold 
Head and near the mouth of the Wanganui can be passed by horsemen only at low tide. On 
foot there is no great difiiculty in making one's way past either bluff even at high tide, except 
when the sea is heavj-, though clambering over the large boulders at the base of the cliffs 
is tiring and fatiguing work. 

Some of the rivers when low have beaches which can be utilised for horse traffic. This 
is the case with all those parts of the large streams which traverse the lowland coimtry. The 
upper parts are less capable of being used in this way. A sure-footed horse, however, can 
be taken from Gribben Flat through the lower gorge of the Mikonui, and in winter-time it 
is possible to ride a horse from Hende's eight or nine miles up the Wanganui River. 

Alluvial Mining Industry. 

General and Historical Account of Alluvial Mining. 

To the Mikonui Subdi-vision belongs the honour of the first- recorded gold-discovery in 
Westland, though as the colour only, made by Jacob Louper, a native of Switzerland, in 
April, 1863.1 A melancholy interest surrounds the discovery, for it was made during the last 
iouruey of the ill-fated explorer George Whitcombe. 

With a view of discovering a practical route from the headwaters of the Rakaia to the 
West Coast, Whitcombe, accompanied by I-ouper, had left Christchurch on the 13th April. 
About the 23rd thev crossed the saddle now known as Whitcombe Pass. The travellers from 
this time met with extremely bad weather day after day, but pushed on as best they could. 
" The Handbook of New Zealand Mines " (1887) describes the discovery of gold on the morn- 
ing of the sixth day after crossing the pass as follows : — 

"Louper, looking towards the bank of the stream, thought he observed some splendid- 
looking washing stuff — fine gravel, mixed with quartz and ironstone. He took the lid of the 
billy, washed about two handfxils, and found some fine specks of gold, or what diggers would 
term ' the colour.' He then washed some more, and laid the gold on a green leaf. When 
Mr. Whitcombe returned he knocked some of the stuff down with the iron point of his compass- 
stick, and Louper went on washing as fast as he could. They got about two grains of fine gold, 
when Mr. Whitcombe said, ' That is enough, Jacob ; we shall claim the reward.J We caimot 

* A road in construction up the Styx Valley and tracks up the Kokatahi and Toaroha Valleys, not 
mentioned in the text, are shown in the map of the Toaroha Survey District. 

t It is probable that colours of gold had been obtained elsewhere in Westland at a prior date, but the 
writer has been unable to obtain definite information concerning any earlier discovery. 

J A reward for the discovery of a goldfield had been offered by the Canterbury Provincial Government. 



23 

spend auy more time here.' He asked Jacob if it would pay to work, and I,ouper, having 
had some experience on the goldfields. rephed that perhaps it would with ground-sluicing, 
but not in any other way : they had not, however, found the bottom, which was always the 
best. Mr. Whitcombe scraped up the gold carefully on a bit of paper, which he tied up in 
a corner of his handkercliief. He spoke of it often, and had great hopes concerning the 
discovery " (p. 103). 

Little more than u week later, poor Whitcombe, almost worn out by hunger and other 
privations, lost his life m attempting to cross the Teremakau while it was swollen by heavy 
rain. 

As far as can be gathered from the Handbook's description of Whitcombe's journey, 
the spot where Louper made his discovery was on the Whitcombe River, one or two miles 
above its junction with the Hokitika.* 

Less than two years after Whitcombe's death began the great rush to the West Coast, and 
it was not long before the gold-seekers had penetrated to almost every locality in the Mikonui 
Subdivision, and in several places had made notable discoveries. The first of these was 
in the lower valley of the Totara River, where, particularly in Fox, Hatter, and othei 
creeks on the western or Mount Greenland side, some very good ground was worked. Sinc( 
the main travel route at this time was along the sea-beach, the auriferous black-sands soon 
received attention. At Donoghue's, about two miles from Ross, the sands proved very rich 
Almost at the same time rich alluvial ground was discovered in the lower valleys of Don- 
nelly Creek and its tributaries, within the boundaries of the present borough of Ross. Tht 
small streams just south of Ross, such as Sailor Gully and Clear or Donoghue Creek, were 
also very productive. Even so early as September, 1865, the estimated population of the 
Totara district was 4,000, and by the end of the year it probably exceeded 6,000 persons, 
the great majority of whom were able-bodied miners. 

In other parts of the subdivision gold was frequently found, but seldom in payable 
quantity. The Totara and Ross districts, however, continued to yield rich returns for the 
next few years. 

At first the poorer localities were abandoned, but as years went on, and the richer diggings 
became exhausted, some little attention was given to them, and in many cases payable re- 
turns were obtained for a time. None, however, proved rich or extensive enough to support. 
more than a few men, and most were soon worked out. 

The dates of these discoveries cannot, as a rule, be obtained, and therefore in the following 
notes the localities will be mentioned in order of river valleys from north to south. 

The head of the Hokitika River has long been known to be auriferous, and was probably 
tested to some extent many years ago. During the summer and autumn of 1906-7, a party 
of prospectors brought stores over the Matliias Pass from Canterbury, and worked the stream- 
bed for some time. It is reported that they obtained more than wages while at work. When 
winter approached, the prospectors, leaving stores and other material behind, abandoned their 
camp. They made their way with great difficulty over Mathias Pass into Canterbury, and, 
since they did not return the next summer, it may be inferred that their earnings did not 
compensate them for the loss of time and hardships undergone. During the winter of 1907 
a fresh attempt was made by Westland prospectors to work the upper Hokitika, but after 
obtaining a small quantity of gold they also abandoned the undertaking. 

At various times small beaches along the course of the Whitcombe and Hokitika rivers 
have given good returns for a time. The best of these were near Vincent Creek, not far from 
the Cropp River ; opposite Frew Creek (probably not far from the locality of Louper's dis- 
covery) ; and near Rapid Creek, which joins the Hokitika a little below the Whitcombe junc- 
tion. A little gold has also been obtamed near the granite gorge of the Hokitika, and at 
other localities the positions of which are uncertain. 

• A translation of the diary which Louper kept during the journey was published in the Canterbury Pro- 
vincial Oazette of the 6th July, 1863. 



^4 

Xix attempt was made to prospect the Hokitika River above the junctioji vith the Whit- 
combe some years ago, but, largely owing to the difficulty of transporting stores up this 
extremely gorgy stream, the prospectors did not penetrate more than five or six miles past 
the junction. During the past autumn some prospectors, using the rough track made by 
the topographical ])arty in 1906-7, have again made their way up this difficult river. 

Many years ago some gold — it is said, about 80 oz. — was obtained near the head of Falls 
Ureek, a small stream which joins the Hokitika opposite Koiterangi Hill. There was some 
excitement over the discovery, but the name of Swindler Creek given to a small branch of 
Falls Creek suggests that it was, in part at least, ill-founded. (See. however, page 158.) 

The streams on the western side of Ford Ridge which drain into the Totara River ha\e 
ail proved gold-bearing to a certain extent. The slopes of Constitution Hill, at the north end 
of Ford Ridge, have yielded a little gold, and only want of water, it is said, prevented pay- 
able results from being obtained. At Totara Forks, where Franklin and McKa}- creeks join 
the Totara, good alluvial gold has been obtained. The western tributaries of the Totara, 
as already mentioned, were found to be very rich. 

Near the top of Moimt Greenland a considerable depth of slightly auriferous material 
occurs. This was worked some years ago under the name of the Alpine Claim. The results 
were not profitable, though it is stated that, could a sufficient supply of water be obtained, 
some of the ground could be payably worked. 

Some of the streams drauiing from Mount Greenland into the Mikonui were rich, notably 
Italian Gully and Redman Creek. Higher up the Mikonui, alluvial gold has been found in 
Bullock and Cameron creeks, streams which drain the north-eastern slope of Mount Rangitoto. 
The streams flowing Iloiu the south-western slope of Momit Rangitoto into the Kakapotahi 
also carry a little gold, but not in payable quantity. DufEer Creek, about eighteen miles south- 
west of Ross, was tried by the early miners and foimd wanting, as its name implies. At a 
later date, however, a considerable amount of gold was obtained from the bed of this stream 
for about a mile above and below where the main road crosses. 

Alexander Creek, which flows from Whaleback Hill, a moraiuic elevation on the south 
side of Duffer Creek, into Ounatai Lagoon, has pelded gold to the value of about £800. 

Near the north shore of Iiake lanthe sluicing operations were carried on for some time 
a few years ago, resulting in the wiiuiing of 400 oz. or 500 oz. of gold. 

Some years ago a small patch of alluvial gold obtained in Evans Creek raised hopes which, 
imfortunately, were not realised. 

The rich black-sands of Donoghue Beacn have already been mentioned. South of the Wai- 
taha as far as the Wanganui Bluff the sea-beach proved very productive in the early "seventies," 
especially seaward of the Ounatai I-agoou, a locality locally known as Hitchin's Beach. 

Dredging. — A few years ago, at the time of the dredging boom in Westlaud and Otago, 
a number of dredges were built and set to work near Ross. All except one were 
utter failures as gold-winners, and have been dismantled. The one exception, the Prince 
of Wales dredge, located in the lower valley of Clear Creek, near Donoghue's. did not at first 
pay its way ; but since it passed into the hands of a small private party, is said to have given 
good returns. 

Methods of working Alluvial Claims and Gold-saving Appliances. 

In the earliest days of gold-mining in Westland the digger was often equipped only with 
the prospector's modest outfit of shovel, pick, and tin dish. Gold was at first obtained mostly 
in the creek-beds, in shallow ground, or on the sea-beaches. "WTien the gold-bearing layer 
was at some little depth below the surface it was extracted by a paddocking method — ^that is, 
making a large hole by throwing the barren surface material to one side, and then renio\dng 
the auriferous layer as it was exposed. Still deeper ground had to be worked by sinking a 
shaft, and dri\'ing out the washdirt : but in such a case water often became very troublesome, 
and could not be kept down by the appliances at hand. The auriferous material was con- 
oentrated by means of cradles, long toms, or small sluice-boxes lined with blanket or plush, into 



25 

which a stream of water was turned. It was not verj^ long before ground-sluicing methods 
came into general use where some thickness of only moderately rich gravel existed and the 
conditions were otherwise suitable. Ground-sluicing gradually developed into hydraulic 
sluicing — ^that is, the use of high-pressure water for breaking down gravel faces. In some 
cases hydraulic elevators were employed for raising washdirt, but at the present time none 
is in use in the Mikonui district. 

Reference will be made on pages 27 a d 28 to the system employed by the Ross United 
I'ompany at Ross and in the Prince of Wales Claim. 

The common method of saving gold by means of sluice-boxes lined with wooden blocks, 
which are cleaned up at intervals, is universally employed in the ground and hydraulic sluicing 
claims of the Mikonui area. The rough concentrate obtained is cleaned by careful streaming 
through a small sluice-box, or is agitated by hand with mercury, and the gold amalgam panned off. 

On the sea-beaches the " black-sanders " often have to wait many weeks or months before 
a payable patch of black-sand " makes." Then they work with feverish energy, scraping up 
and removing the black-sand above high-water mark, to be washed when time is available. 
Their gold-saving apparatus consists of an amalgamated copper plate about 3 ft. long by 2 ft. 
wide, set on a portable wooden frame with an inclination of about 1 in 6. At the head is a small 
distributing-box, into which the sand is shovelled. Somevimes a small stream of water can 
be turned into the distributor, but generally it has to be baled from an adjoining creek, or 
carried in kerosene-tins from the sea. The loose amalgam is .scraped up at the end of a day's 
work, and the mercury driven off by heating the amalgam in an old shovel over a wood fire 

The dredges that have worked in the district were ladder and bucket dredges employing 
the usual Otago methods of gold-saving — namely, revolving sorting-screen, tables with cocoa 
nut mattitiu. &c. 

Auriferous-quartz Mining. 

Numerous (quartz reefs occur in the Mikonui Subdivision, more particularly in an area 
largeh- occupied by grauwackes and argillites of supposed Carboniferous age (Maitai Series of 
Cox and McKay), which ex-fends from Koiterangi Hill to the Kakapotahi River. At one time 
and another quite a number of small quartz-mines have started operations in this area, espe- 
cially in the vicinity of Ross. One of the earliest of these enterprises" was located in Bayley 
Creek, about a mile from Ross. A five-head-stamper battery was built, and from time to 
time quartz from the small veins in the neighbourhood was treated, apparently on behalf of 
different claimholders. According to the Mines Report of 1895, the battery crushed during 
the pre( eding year 157 toiis of quartz for a return of 90 oz. The next year's report records that 
142 tons were treated on behalf of Yarvvorth and party for 70 oz. of gold, whilst Wilhams 
and part\- crushed an unspecified (|uantity of (|uartz for a like return. 

During the last two years (Jsineis and party have vigorously prospected with satisfactory 
results, a smair reef in the same neighbourhood, which will be again mentioned on a later page. 
A five-head battery driven by a Pelton wheel has been erected, and mining operations are now 
proceeding. The full returns have not Ijeen made public, but it is understood that they are 
highly payable, and it is known that in two crushing-periods 80 tons of quartz were treated 
for a total return of 95 oz. of retorted gold, valued at £365 5s. 

At Cedar Creek (N'eronica). on the south-eastern slope of Mount Greenland, go'd-bearing 
quartz lodes were discovered about 1885. The principal claims were the William Tell and 
the Swiss Repubhc. Development-work was carried on for some time, and expensive roads 
were made to the locality. Two small batteries were erected, but neither crushed for any 
length of time. The writer has been unable to find any official record of the results obtained, 
further than that during 1889 they were disappointing.* Finally the claims were deserted ; 
but about 1896 they were again taken up, and a company called the Alpha did some work. 
Once more abandonment of the ground took place. In 1907 the Cedar Creek reefs were for 

♦ Miaea Report, 1890, C.-3. p. 1(52 



26 

a third time taken up by a prospecting syndicate, which has reopened the old workings and 
made tests of the ore, with results unknown to the writer. 

Near the head of Farmer Creek a quartz reef was worked a number of years ago by Antonio 
Zala and others. A small battery driven by a water-wheel was constructed, but evidently 
the returns were disapjiointing, for active operations soon ceased. 

The crushing machinery in all these batteries consisted of four to ten heads of light 
stamps, and the gold-saving plant of amalgamated copper plates, with or without the addition 
of a small berdan. 

Silver-mining. 

Over thirty years ago a small quartz vein carrying pyrite, galena, and other sulphides 
was discovered on the upper slopes of Mount Rangitoto. Samples of ore sent to Melbourne for 
assav were reported as yielding silver at the rate of 392 oz. and 735 oz. to the ton, and largely 
on the strength of these results a company with a large capital was floated. The company 
carried on operations for several years, and speyt many thousands of pounds in opening out 
the lode, erecting treatment plant, &c. That, however justifiable prospecting operations 
may have been, the bulk of this mone}' was absolutely wasted admits of no question. 
Samples of the ore were repeatedly assayed l)y the Colonial Laboratory from 1876 onwards, 
but the results as a whole were not satisfactory, the assays usually running only a few ounces 
of silver to the ton.* Much of the Rangitoto ore contains greater values -in gold than in 
silver — a fact which apparently was first noted by the late Mr. William Skey, formerly Colonial 
Analyst, in 1876. f 

COAL-MINING. 

From time to time prospecting for coal has been undertaken in the Mikonui Subdivision 
both in likely and unlikely localities, but the results have not been satisfactory. Many years 
ago outcrops were discovered in the Koiterangi HUl shales, and some work done, but the seams 
proved to be of poor quality, small, and broken. Coal has been reported as occurring on 
the west side of the Hokitika, near Doctor Hill, and a very thin seam, of mipromising 
character, was discovered in the valley of Coal Creek, near Ross, some years ago. 

Special Mining Areas. 
Boss Flat. — No piece of alluvial ground has ever been discovered elsewhere in New Zea- 
land equal in richness to Jones Flat, the gently sloping gromid which forms part of the Ross 
Flat, and is traversed by Jones Creek, a small branch of Donnelly Creek. Gold was first dis- 
covered towards the end of 1865 in the bed of Jones Creek, but before long it was found that 
rich layers of washdirt existed in the neighbouring terraces and flat. The ground was taken up 
under miners' rights, in small claims, which were worked in several ways, but principally by 
sinking shallow shafts, from which the ground was blocked out. The gold-bearing layers 
were found to dip seaward, and as they were followed down water became troublesome. By 
amalgamation, repegging of abandoned ground, &c., larger claims were brought into existence, 
and pumping appliances of various kinds were installed. Finally a drainage company 
was formed, which undertook the unwatering of the claims in return for a contribution from 
each of the companies interested. About this time a shaft was sunk to a depth of 300 ft. by 
a claimholder named Cassius, who located a highly payable layer of washdirt and for a time 
reaped remarkably rich returns. During a period of nine or ten months three of the claims — 
namely, that owned by Cassius, the Morning Star, and the Excelsior — obtained between 
them 11,543 oz. of gold, worth £43,865 10s. J The pumping machinery proved inadequate, 

* See G.S. Rep. 1874-76, vol ix, 1877, p. xii of Introduction, and p. 87 ; also " Eleventh Report on 
Colonial Museum and Laboratory, 1876," p. 22 ; and " Twelfth Report on Colonial Museum and Laboratory, 
1878," p. 32. 

■\ Eleventh and Twelfth Reports on Colonial Museum and Laboratory, loc. cit. See also assay results in 
Chapter xiv. 

X Mines Report, 1887, p. 43 of report by Mr. H. A. Gordon, F.G.S., Inspecting Engineer, on Goldlields, 
Roads, Water -races, &c. 



27 

though the amount of water to be raised did not exceed 800 gallons per minute, quite a mode- 
rate quautit}^ for a field of this character, and after a short career the drainage company 
ceased operations. This was in 1872. The claims on the Ross Flat were now practically 
abandoned, but probably work was carried on in a desultory kind of way for some years. At 
last a company known as the Ross United acquired possession of nearly all the original claims 
on the flat, as well as of a considerable area of new ground. An adit, 98 chains in length, 
including a short length of open ditch, was constructed from near the sea-coast, and drained 
the company's claim to a depth of 90 ft.* from the surface. The company sank a shaft on 
the terrace behind the town, which was lost through suspeudmg sinking while in quicksand, 
and another shaft was then put down just below the terrace. This shaft, which reached a 
depth of 392 ft., is stated to have passed through seven or eight gold-bearing layers. After 
several prospecting-drives had been made, payable gold was struck. At the end of a few 
months, however, the workings were drowned out, owing to the inadequacy of the pumping 
machinery. As far as can be learned from the old records, gold to the value of £9,170 was 
won from the deep workings of the Ross United. After 1887, the date when pumping was 
stopped, the Ross United Company let part of their ground to tributers, and worked a portion 
of the remainder down to the drainage-adit level by means of an open paddock. The system 
followed was to break down the face of the paddock by hydraulic sluicing, run the material 
through sluice- boxes, and then lift the tailings to the surface partly by means of bucket- 
elevators, partly by an inclined tramway worked by water-power. The water was allowed to 
run away through the drainage-adit. By this system a considerable amount of gold was 
won ; but a niunber of years ago the company ceased operations on the flat, and finally the 
groimd was abandoned. 

Several years ago 100 acres of the Ross Flat was reserved by the Government 
as a special claim, and £15,000 offered as a subsidy to any person or company taking up the 
area and spending £50,000 under approved conditions on its development. 

In 1906 a company called the Ross Flat Goldfields was formed to work the Ross Flat. 
It decided to cniploy electricity derived from water-power for driving the pumps and other 
machinery. Lake Kanieri was selected as the source of the water-power, and at the present 
time the necessary electrical machinery, power-houses, and conveying-line are in course of 
erection. Four Worthington high -lift four-stage turbine pumps, each capable of lifting 1,000 
gallons per minute, are to be installed. Two of them are to be horizontal fixed pumps, and the 
other two sinkuig-pumps, which can be raised or lowered as required.f 

Mont d'Or Gold-mining Company. — This company started hydraulic sluicing in Sailor Gully 
about 1882, and was successful almost from the start. After a few years it bought the claim 
and water-race of the adjouiing GrcenlaJid Company. It has a share capital of £12,000, of 
which amount £10,800 is paid up. At the end of 1907, 31,699 oz. of gold, valued at £123,838, 
had been won since the formation of the company, whilst the dividends declared amounted 
to £43,800. At the present time the company is working a high face of coarse gravels, and 
appears to have a life of many years before it 

Donoghue's. — This locality, which is about two miles south-west of Ross, was at one time 
noted for the richness of its beach-sands. In early days good gold was discovered in Donoghue 
or Clear Creek, and alluvial mining carried on for some time till all the gold near the surface 
had been won. Much of the ground hereabouts in the course of time passed to the Prince 
of Wales Company, which finally sold out to the Ross United Company. The latter concern 
worked the claim by a system of hydraulic sluicing and bucket- elevators, similar to that already 
described as used by it on Ross Flat, the ground for some distance below the surface being 
drained by an adit level driven from the sea, exactly as at Ross. This system of working proved 

• Cox (Rep. G.S. during 1882, vol. xv, p. 52) gives 75 ft. as the depth, but the discrepancy is caused 
by the use of different datum points. 

t For further information concerning this company and Ross Flat, see Mines Report, 1907, C.-3, p. 8, 
and accompanying map. 



28 

profitable for a number of years, but in the end the operations ceased. As mentioned on 
page 2-1, under the head of " Dredging," the ground i,s now yielding payable results to a 
dredge. 

McLeod's Terrace Sluicing Company. — This concern was formed a few years ago in order 
to work the gold-bearing gravels of McLeod's Terrace, on the south side of the Mikonui River. 
A large water-race was made, and a face opened out, but so far the results have been unsatis- 
factory. This is all the more disappointing, because the ground, which is exactly like that 
of the successful Mont d'Or Claim, undoubtedly shows good prospects in places. 

Water-races. 

During the early years of the mining industry a great number of water-races were con- 
structed in the subdivision, chiefly in the Ross-Totara Goldfield, In 1889, 120 races were 
registered at Ross, with a total length of ninety miles. The largest of these were the Ross 
United Water-race, which brought water from Donnelly Creek to the Ross United Claim : 
the Mont d'Or Water-race, which takes its water from Gagliardi Creek and other branches 
of Donnelly Creek ; the Greenland Company's Water-race, starting from Medhurst Creek, 
well up the western slopes of Mount Greenland ; the Alpine Water-race, high on Mount Green- 
land ; and the Prince of Wales Water-race, which brought water to the claim at Donoghue's 
from Campbell Creek, a tributary of the Lower Mikonui. So)ne of the races just mentioned 
as well as others are still in use. but the great majority, having served their original purpose, 
have been abandoned, and are now out of repair. 

Many years ago a race was projected to bring water into Ross from the Upper Mikonui by 
way of the Totara Saddle and a long tunnel through Malfroy Spur. A detailed survey in 
connection with the work was made and the tunnel partly constructed. The lower three 
miles of the race was completed, and is now being used by the Mont d'Or Sluicing Companv. 
No less than £25,644 was spent on this undertaking, but it has been estimated that to com- 
plete it would cost £60.000.* 

The only race which has been made during recent years belongs to the McLeod's Terrace 
Sluicing Company. This large and excellently constructed race begins on a branch of Mos- 
quito Creek, and runs to the company's claim dear the Mikonui River. At present it does 
not carry anything like its full capacity, but by extending it two or three miles to the Kaka- 
potahi River an ample supply of water could be obtained. 

Gold-production. 

The only mineral which has been produced in notable quantity in the Mikonui Subdivi- 
sion is gold. Unfortunately it is impossible to compile even approximate figures of the total 
yield from the official or other records available. It has been stated that over 5 tons of gold 
(163,333 oz.) has been obtained from -Jones Flat alone. f In all probability the total gold- 
production of Ross and neighbourhood, including the Totara Valley, the Mont d'Or Claim, 
and Donoghue's, is considerably greater than this amount, and may reach 300,000 oz. or 
more. In other parts of the subdivision the yield of alluvial gold has not exceeded 10,000 oz. 
or, at most, 15,000 oz. Up to the present time the returns of gold from the various quartz- 
mines total only a few hundred ounces. 

Timber Industry. 

There are large areas of land in the Mikonui Subdivision covered by timber fit for milling, 
but hitherto these have been little utilised. The pa'incipal forest area is the lowland comitry 
between the Mikonui and Wanganui rivers, which contains a very large amount of rimu 



* Mines Report, 1887, p. 16 of report by Mr. H. A. Gordon on Goldfields, Roads, Water-races, &c. 
t Mines Report, 1906, C.-3, p. 109. 



PLATE VIII. 




llYDliAUl.IC Sl.UlCI.Ni, AT liu.-.^ LmTIU) L'LAIM. Ll.EV ATUliS. AM) 1*1 l'i;-J,l^'E IX FOUKGJiOUAD. 
Fnun y .'/,. Miiiiiii/ IldiiilhooJ.-.] 








^^^^^.■..: ^.^'j^ 



•^->cT 



■'^y--^^^ 



Hydiiallic Si.ukim; at Mo>t u t'lt (_ i.aim, l^o^!;s. Nozzles at Woiik o.\ a 11ii;h Face of 

Fl.UVIO-GLACIAL GrAVELS. 
Frtiiii X./. MiniiKj I[nnilho(i):.~\ 

(JtiA. Bull. Xo. /;.] [To fare page 28. 



29 

(red-pine), kahikatea (white-pine), silver-pine, and other valuable timbers. Near Ross a good 
deal of timber was sawn in past years, but now the only sawmill in the subdivision is a small 
plant near Bold Head, which up to the present time has been employed chiefly in cutting 
silver-pine for railway-sleepers. A few bushraen are engaged here and there in dressing by 
hand silver-pine sleepers, or in sawing niatai (black-pine) and other timbers for the wooden 
blocks usually employed in lining sluice-boxes and tail-races. 

When the railway reaches Ross there will probably be a considerable extension of the 
timber industry, but the greater part of the forest south of the Mikonui must remain uncut 
till the railway is extended to the neighbourhood of the Waitaha River, or even further south. 

Agricultural and Grazing Industries. 

At present the principal areas in the Mikonui Subdivision utilised for agricultural pur- 
poses are the upper part of the Koiterangi Plain (the lower part is outside the subdivision), the 
lower valley of the Totara River, the modern coastal plain north and south of the Mikonui 
River, and the flood-plains of the Waitaha and Wanganui rivers. In the upper valley of 
the Mikonui is one isolated settler, and a beginning has been made towards clearing the upper 
Kakapotahi \'alley by some intending settlers who have taken up land in that locality. 

As already stated, the amount of cleared land in the Mikonui Subdivision is not large. 
The settlers devote themselves almost wholly to the raising of cattle, sheep, and horses, growing 
practically no cereals, and only small quantities of root-crops. The river-beds and adjoining 
open spaces support considerable numbers of sheep and cattle. The forest lands are also 
made use of to a small extent by running cattle upon them. These thrive well upon the 
succulent leaves of the patete or five-finger (Schefflera digitata) and other shrubs of the 
forest undergrowth. The Prince of W'ales's feather fern (Todea swperha) is also relished by 
cattle. 

Though a large portion of the subdivision can never be made useful to the farmer or 
grazier, there is considerable scope for the extension of agriculture as population increases 
and facilities for communication are extended. Already a large number of sections have been 
taken up t)y intending settlers, who have made various improvements, such as fences and 
small clearings, in their properties. 

Dairyincf. — In the course of time the dairying industry will be largely developed in the 
subdivision. One or two of the settlers in the upper part of the Koiterangi Plain supply 
milk to the Koiterangi Creamery, a branch of the Koiterangi Dairy Factory. When settle- 
ment has progressed a little further, a creamery will probably be started on the upper part 
of the plain also. Butter-factories at Ross and in the Waitaha Valley are already spoken of. 
Preliminarv steps for the establishment of a cheese-factorj' on the south side of the Wanganui 
have been taken, but the unbridged state of that river is a drawback, since the land- 
holders on the north side will not be able to send milk regularly to the factory so long as a 
bridge is wanting. 

Honey. — On the south side of the Mikonui River one of the settlers has an apiary, with 
a modern extractor plant, and turns out large quantities of excellent honey. 

Flax. — There is a flax-mill on the western bank of the Kokatahi, which draws its supplies 
from the adjoining swamp. At the mouth of the Waitaha River a small flax-mill was in 
operation some vears ago, but on most of the fibre being cut out the mill was closed down 
and thfe machinery removed- 
There are large areas of the subdivision particularly suitable for the growth of flax, and 
in all probability its cultivation on an e.xten(led scale will in the course of rime become an 
important industry here and elsewhere in Westland. It is perhaps as well to say that the 
plant referred to is New Zealand flax (Phormium tenax), a monocotyledonous plant very 
different from the European flax (Linum usiiatissimum), which also could be successfully 
grown in Westland. 



30 



CHAPTER III. 



OUTLINE OF THE GEOLOGY. 



Page 1 Page 

Sequence and General Structure of the j Periods and Directions of Folding, Ele- 
Several Formations . . . . . . 30 vation, Depression, & c, . . . . 35 

Geological History . . . . . . 32 | 

Sequence and General Structure of the Several Formations. 

Though in some respects the geology of the Mikonui Subdivision is fairly simple, it also 
presents problems of a difficult order. The sedimentary formations represented are few in 
number, and their stratigraphical relations are not difficult to make out. On the other hand, 
the almost entire absence of fossils from the older formations and the intense metamorphism 
which they have undergone render the determination of their age more or less problematic. 
Faulting, too, has caused a considerable amount of complication in several areas. 

The oldest rocks within the subdi\'ision belong to a great series of intensely folded rocks 
chiefly of sedimentary origin — the Arahura Series of this and of the Hokitika Bulletin. The 
folding, which, as seen in the Southern Alps, is probably of comparatively recent origin, is 
directed from north-east to south-west. The dip, except where affected by local causes, 
is everywhere at high angles. 

The Arahura Series has been considerably affected by faults, which, with certair- 
notable exceptions generally appear to be due to tension movements, and have resulted in the 
production of many zones of crushed rock. These crushed zones have materially assisted 
in the formation of the valleys, mountain-saddles, &c., owing to their ready removal by 
denuding agents. 

At the base of the Arahura Series (and in this bulletin tentatively included with it) is a 
considerable thickness of highly metamorphic rocks of peculiar character. In part they 
were probably originally sedimentary, but contain belts of much-altered igneous rocks. The 
lowest layers are light in colour, and generally have the appearance of gneiss, while the upper 
layers consist of dark schistose rocks. These rocks seem occasionally to enclose bands ol 
younger, less altered rocks, and present problems both in respect to origin and to age which 
are difficult of solution. In the Hokitika Subdivision rocks of this type were seen only in 
one or two localities, but in the Mikonui area they are notably developed. 

These gneissic and dark schists, as they wnll be called in this bulletin, have been noted 
by Cox, Von Haast, and McKay, but until the present survey, never closely examined. They 
are greatly intruded by bosses of granite (using the name in the field sense), into which they 
sometimes seem to pass more or less gradually. It is thought that these granitic intrusions 
took place during the earlier stages of the alpine folding — that is, probably at the end of the 
Cretaceous era, or at the beginning of the Tertiar}\ In some areas the gneissic schists con- 
tain many basic dykes of Tertiary age : in others dykes are almost absent. 

The gneissic schists are succeeded, apparently quite conformably, by an enormous thick- 
ness of highly metamorphic micaceous schists, which towards the alpine divide gradually lose 
their intensely altered character, and finally pass into very slightly schLstose grauwackes, 
quartzites, and argillites. In the whole series there is no distinct break or unconformity of 
anv kind to be detected, and therefore, in the absence of all fossils except the annelid and the 
supposed Dentalium mentioned on a later page, any division made must depend upon 
lithological characters. 



31 

Most investigators consider that the beds composing the Arahura Series vary consider- 
ably in age. Von Haast would assign to these rocks an age extending from Archaean to Car- 
boniferous* ; whilst McKay appears to classify the lower beds as Archa?an,t the middle and 
upper as Devonian, Carboniferous, and possibly Permian. J In the present bulletin the upper 
beds of the Arahura Series will be regarded as equivalent to the Maitai Series, considered 
by McKay to be of Carboniferous age, whilst the middle and more especially the lower beds, 
though placed in the same series, will be regarded as of uncertaio Palaeozoic age. 

The middle horizon of the schistose rocks has been intruded by sill-like masses of ultra- 
basic composition, which were originally dunites or allied rocks, but have been in great measure 
altered to serpentine, and even to talc. These ultra-basics form the Pounamu Formation of the 
Hokitika Bulletin and of the present pubUcation. Their age is probably much the same as that 
of the eariy alpine building movements. In the neighbourhood of the serpentine outcrops the 
mica-schists have been more or less affected by infiltrating magnesia-bearing solutions, which 
were genetically connected with the ultra-basic intrusions. 

Another development of old sedimentaries, in this bulletin called the Greenland Series, is 
typically seen at Mount Greenland, near Ross, and occupies a considerable area in the Totara 
Survey District. It consists of grauwackes and argilUtes, and is easily correlated with the 
Kanieri Series of the Hokitika Bulletin, but its exact relationship to the Arahura is uncertain. 
Cox and McKay, however, place it in the Maitai Series of probable Carboniferous age, and 
correlate it with the upper part of the Arahura Series. In any case it was almost certainly 
formed during the same great period of sedimentation as that in which the whole or at least 
the greater part of the latter series was depo.sited. 

The Greenland rocks are less stronglv folded than those of the Arahura Series : and 
the general direction of the strike is north-west and south-east, almost at right angles to the 
strike prevailing in the rocks of the main mountain -chain. This folding is older than that now 
possessed by the Arahura beds. As will be explained later, a great reversed fault separates 
the rocks of the Greenland Series from the rocks of the Arahura Series, and they are much 
less affected by dynamic metamorphism than the middle and lower parts of the latter series. 
A nximber of large tension faults traverse the Greenland beds, more particularly in the neigh- 
bourhood of Ross. 

Several large granite bosses intrude the rocks of the Greenland Series, and, it is believed, 
have preserved the area occupied by it from being faulted below sea-level with the rest of 
the ancient land that once existed westward of the present ooast-line.§ 

A great stratigraphical break follows the Palaeozoic rocks, the next sedimentarj- forma- 
tion represented in the area being the Cretaceo-tertiary or Coal-bearing Formation of Sir 
James Hector. It seems probable, however, that the principal coal-bearing rocks of New 
Zealand must be considered purely Tertiary, and in this bulletin the Koiterangi Series, as the 
coal-measures of the subdivision are called, will be regarded as of Older Tertiary (Eocene- 
Oligocene), or even possibly m part of Lower Miocene age. 

The rocks of the Koiterangi Series are of subsequent date to the folding of the Greenland 
rocks, and probablv to the major folding of the Arahura Series, but everywhere have decided 
tilt, induced bv tensional faulting movements. The strike generally approaches north and 
south, and the dip is usually to the east. 

Following the Koiterangi Series are certain local conglomerates, sandstones, and clays, 
which from their fossil contents are probably of Upper Miocene age. It is difficult to say 
whether or not there is any marked stratigraphical imconformity between these rocks and the 
Koiterangi Series. Like the rocks of the latter series, they have been much disturbed by fault- 
movements, and near Ross the dip approaches 90°. The sandstones and clays may be cor- 



* "Geology of Canterbury and Westland," 1879, p. 2.51. 

t Sollas and McKay : " The Rocks of the Cape Colville Peninsula," (and other localities), vol. ii, 1906, p. 198. 

X "The Geology of the Northern Part of Westland," Mines Report, 1893, C.-3, p. 171. 

§ See "Geological History," pp. 32-35. 



32 

related with the Blue Bottom of the Holdtika Bulletin. They are followed, it may be almost 
conformably, by ancient river- gravels, which h.ive a limited exposure near Ross, and may be 
correlated with the Moutere Gravels of Hector and McKay — that is to say, with the deposits 
of the hypothetical Moutere River, which, it has been supposed, ran in early Pliocene times 
from south of Ross to Blind Bay. These gravels have been affected by fault-movements which 
accompanied the last period of uplift, and in at least one place in the neighbourhood of Ross 
show evidence of tilting. 

The Moutere Gravels are succeeded with some degree of unconformity by a vast series 
of morainic, fluvio-glacial, fluviatile, and marine gravels, the formation of which belongs to 
the last cycle of erosion, and is still actively proceeding. 

The table on the next page shows the classification adopted by the various authors who 
have published descriptions of Westland geology. One or two slight alterations have been 
made in the original arrangements, in order to enable a comparison of one classification with 
another to be more easily made. 

Geological History. 

Until a detailed geological survey has been made of a considerable portion of New Zea- 
land, any attempt to give the geological history of. an isolated district must necessarily be 
more or less tentative. In the following paragraphs an endeavour will be made to present 
the history of the area under consideration in such a way as to be consistent with the views 
expressed throughout the bulletin. As the geological survey is extended, no doubt it will 
become necessary to modify these opinions. 

There is little to tell us what were the physsical conditions in the Palaeozoic periods of 
the area now occupied by the Mikonui Subdivision. Contemporaneously with the deposition 
of the lowest beds of the Arahura Series there was probably a period of vulcanism, during which 
igneous rocks of intermediate type were poured out on the surface or injected into the strata. 
A consideration of the nature of the sediments comprising the upper layers of the Ai-ahura 
Series shows that they are composed chiefty of angular or subrounded grains of quartz, acid 
feldspars, and mica, and were therefore probably derived from a land-surface largely consisting 
of granitic or gneissic rocks. The original constituents of the micaceous schists and the sup- 
posed sedimentary portions of the gneissic schists can no longer be recognised, but the absence 
of any definite stratigraphical break and the similar chemical composition make it quite 
possible that they were derived from the same land area. Since rocks resembling those of 
the Upper Arahura occur in many parts of New Zealand, it has been conjectured that this 
region was in Palseozoic times the foreshore of an ancient continent. Whether this continent 
lay to the east or west of the present main structural axis is somewhat doubtful. It might be 
supposed that some indication might be given by the greater coarseness or fineness in grain of 
the old sedimentaries as they are followed from east to west. The method, however, has not 
given decisive results, probably owing to the difficulty of identifying corresponding layers at 
distances of, say, a few miles apart. Hutton's view, however, may be accepted, and the 
continental land assumed as having been to the west. There are reasons outlined below 
for believing that this was the case. The sediments appear to have been laid do'wn in com- 
paratively shallow water, and their great thickness is proof both that the land-mass from 
which they were derived persisted for a very long time, and that its foreshore, or, roughly 
speaking, the present land-surface of New Zealand, gradually sank throughout the whole of at 
least one great geological period. 

Since, as already inferred, the ancient continent consisted largely of granite or gneiss, it 
may be conjectured that its rocks belonged to an Archsean complex, similar to those appearing 
in the Laurentian protaxis of Eastern Canada and forming a great part of Scandinavia and 
Lapland. The buttress of gneissic rocks forming Western Otago may possibly be a remnant of 
this ancient land-mass. The probable extent of the ancient land need not here be discussed, 
but it may be remarked that some writers have regarded New Zealand as having in Palaeozoic 



88 



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34 

periods formed part of the lost Gondwaua continent,* and in Mesozoic times as being connected 
with an Australo-Indo-M.alay land-massf. 

It is certain that the ancient land was in existence during the Maitai or Carboniferous 
period ; and, though no evidence can be obtained in the Mikonui Subdivision, it is probable, 
judging from the descriptions given of the Triassic and Jurassic strata of other parts of New 
Zealand, that it persisted, with various fluctuations of level, until the end of the Jurassic 
period,! and perhaps later. 

At some time during the Mesozoic era, probably about the end of the Jurassic 
period, the sediments of the Greenland Series were strongly folded along north-west and south- 
east lines. This folding extended over the area now occupied by the alpine chain, and is thought 
to have been part of a general earth-movemetit, which afiected large areas of Palaeozoic and 
Early Mesozoic rocks, throughout the greater part of the South Island. There seems to be no 
escape from the conclusion that the rocks of the Aiahura Series shared in the folding, although, 
as previouslv mentioned, they now exhibit folds which trend from north-east to south-west. 

The history of the area during the later Mesozoic periods is uncertain ; but at the beginning 
of the Tertiary era there began a period of elevation and mountain-building during which any 
late Mesozoic deposits that existed in the area were removed by denudation. New Zealand 
for the last time became part of a continental land which stretched far to the north, and, if 
not actually connected with New Guinea and the Indo-Malay Archipelago, was so far in touch 
with these regions that many new animals (including most of our land birds) and plants were 
introduced from that quarter.§ 

Probably at this time the north-east and south-west folding along the line of the Southern 
Alps was inaugurated, or, if it had originated at an earlier period, was renewed, with the result 
that a high mountain-range came into existence. Whether this range formed the main water- 
parting between east and west, as do the present Alps, or whether another mountain system 
west of the present coast-line fulfilled this function, is doubtful. In support of the opinion 
that a considerable extent of land at this time existed west of the alpine chain may be 
mentioned the uplifted peneplained area consisting mainly of ancient rocks belonging to the 
Greenland Series, which still remains. McKay, with much reason, holds the view that there 
was land of mountainous character in this area till the Pliocene period.]! 

Whatever the exact land-forms may have been, it is tolerably certain that in the vicinity 
of the Mikonui Subdivision there was mountainous comitry subject to glaciation, as well as 
to the action of nmning water, for the lower beds of the conglomerates which form the base 
of the next formation — ^the Koiterangi — are very coarse, containing huge boulders many 
feet in diameter. These conglomerates consist almost entirely of grauwacke pebbles, with a 
few pieces of argillite and rather numerous fragments of quartz. Since they are exactly 
such as would be derived from an area occupied by rocks of the Greenland Series, it may be 
concluded that this was the case. The entire absence of granite and mica-schist from the 
conglomerate is most remarkable. It would therefore seem that neither granite nor the 
metamorphic rocks of the Arahura Series as yet formed part of the land-surface. 

It may be supposed that the granites, gneisses, and schists exposed at the present day were 
covered by grauwackes and argillites of the same character as those forming the Greenland 
Series, and that the denudation of these furnished the materials of the Koiterangi conglomerate. 
The view that the conglomerates were derived, or partly derived, from high land to the west 
is a'so permissible. 

A considerable depression of the land now began, and, as it went on, the coarse con- 
g'omerates were succeeded by grits and fine sands. The subsidence continued until much at 

* p. Lemoine: " litudes Geologiques dans le Nord de Madagascar," 1906, p. 464. 
I Loc. cit., p. 466. 

j See, ivter alia. Bulletin No. 4 (New Series), N.Z.G.S., p. 23, for evidence of a Jurassic and pre-Jurassic 
continental land mass, of which New Zealand either formed a part or was the foreshore. 
§ Hutton and Drummond : "Animals of New Zealand," 1904, p. 17. 
1| " Geological Explorations of the Northern Part of Westland," Mines Report, 1893, C.-3, p. 181, 



36 

least of the area was covered by the sea, the result being the formation of layers of limestone 
and calcareous sandstone, which at Koiterangi Hill attain a thickness of about 250 ft. About 
thirty miles north of Koiterangi, however, the marine sediments have a thickness of several 
thousands of feet, so that probably the depression of the land was not so marked in the Mikonui 
area as it was further north. Nevertheless this subsidence was not local, but general all over 
New Zealand. 

Throughout New Zealand the fossils of the marine beds overlying the workable coal- 
seams have an unmistakable Tertiary facies, and therefore there need be little hesitation 
in considerin^g the Koiterangi Series to be of Tertiary age. 

After the deposition of the coal-measures, the ancient alpine range was worn down to 
such an extent that the schists and granites became exposed, and a peneplain, described in 
the next chapter, was formed over at least the greater part of the Mikonui Subdivision. Very 
soon, however, re-elevatiou of the Alps seems to have taken place. Between the Alps and 
the land to the westward a shallow arm of the sea remained, or was formed by local sub- 
sidence due to faulting, and in this the Upper Mocene beds, of which only small patches occur 
m the subdivision, were laid down. Since the Blue Bottom of the area immediately to the 
north undoubtedly contains ice-striated stones, as well as pebbles of schist, serpentine, and 
other rocks occurring in the present alpine area,* it is probable that the Alps now rose well 
above the snow-line, and were glaciated. 

Towards or at the close of the Upper Miocene further land-elevation began. The areas 
occupied by the Upper >Locene beds were raised above sea-level, and the arm of the sea in which 
they were deposited became a river-valley, in which gravels corresponding in character to the 
Moutere Gravels of Northern Nelson were laid down. These gravels as they appear in the 
Mikonui Subdivision consist largely of the reassorted Koiterangi or coal-measure conglomerates, 
and in all probabilitv a similar statement applies to many of the exposures outside the sub- 
division. 

After the formation of the Moutere Gravels still greater changes took place. Whatever 
was left of the old land westward of the present coast-line disappeared ; the Alps rose higher 
and higher, and soon great glaciers came creeping down from the snowfields. A factor of con- 
siderable importance in bringing about the advance of the glaciers may have been the increased 
precipitation on the alpine slopes, caused by the submergence of the protecting western land. 
Whether the climate aj)preciably increased in severity is doubtful : in fact, it may even have 
become milder in the lowlands through the approach of the sea. The glacial rivers broke up 
and reassorted the Moutere Gravels, and the glaciers, ever advancing, all but completed the 
work. Finally, as the denuding forces reduced the height of the mountains, and by carving 
out deep vallevs decreased the area of the snowfields, the glaciers began to retreat. Possibly 
their recession was hastened by a slight increase in the annual teraperaturet, but of this nothing 
definite can be said. As the glaciers receded they left l)ehind them many moraine or rock- 
dammed hollows, which for a time became lakes. Since the retreat of the glaciers into the 
mountains during the Pleistocene— a retreat still slowly proceeding— the rivers have deepened 
their alpine valleys and carried a vast amount of material into the lowland country and into 
the sea. This has filled the old moraine-dammed lakes, with the exception of the area now 
occupied by Lake lanthe, and built up the various river and marine terraces, the modem 
coastal plains, &c., but otherwise no noteworthy geological changes have taken place. 

Periods and Directions of Folding, Elevation. Depression, etc. 
Owincr to the great importance of folding in connection with periods of general land- 
elevation "soTue further remarks on this subject seem to be called for. In the first place, it 
must be admitted that great difficulty has been experienced in gmng even a roughly con- 
sistent account of the geological history of the Mikonui area, and, rightly or wrongly, it has 



* Bull. No. 1 (New Series), N.Z.G.S., 1906, pp. 85-88. 
+ Perhaps also by a subsidence of the Und as a whole, 
3*— Mikonui. 



36 

seemed necessary to run in a measure countci- t(j the views of Hochstetter, Hutton, Von Haast, 
and other eminent geologists regarding the age and structure of the Southern Alps. 

Hutton, who has on several occasions ably set forth the geological histoiy of New Zealand, 
considered that during the Middle Devonian, folding (accompanied by elevation) took place 
in a belt parallel to the present main mountain-axis, but some distance to the west of it. Early 
in the Permian (probably), elevation with rock-folding again occun'ed in the same belt. The 
present alpine area, he thinks, was to some extent involved in the Permian movement, if 
not in the earlier one of Devonian age. About the middle of the Jurassic period, folding 
of the rocks again occurred along the same north-east and south-west axis ; the Alps were 
formed, never again to be wholly submerged. But as they now stand, the Alps are " only 
the eastern half of a huge geanticlinal arrangement of contorted rocks, the western half having 
been washed away by the heavy rains which fall upon that side." Again, a little before the 
Tertiary era, folding (accompanied by elevation) once more took place, giving the last touch 
to the internal structure of the mountains. A marked Pliocene elevation is considered by 
Hutton to have been continental, and not accompanied liy any decided folding of the main 
moimtaiu-ranges of New Zealand. 

In the paper* from which these views have been abstracted Hutton does not refer to the 
north-west and south-east folding, which is considered by Gregory, and perhaps Marshall,! 
to be older than the north-east direction of folding, whilst Suess, relying apparently chiefly 
on Hochstetter's and Hutton's publications on New Zealand geology, considers it to be of 
the same age, for he speaks of it meeting the alpine folding in syntaxis.J 

There are, however, certain facts which are apparently irreconcilable with Hutton's 
views or with those expressed by Hochstetter, Suess, and others. In the first place, evidence 
has been adduced by McKay§ supporting the view that before the Miocene the present Alps 
did not exist as a mountain-chain. Some confirmation of McKay's opinions is brought forward 
in this bulletin, although it is believed, and in fact is certain, that there was at least one earlier 
period of folding along the alpine axis. In the second place, the occurrence of rocks folded in a 
north-west and south-east direction , immediately west of the alpine chain and separated from it 
only by a huge fault must be regarded as a fact completely opposed to Hutton's " huge geanti- 
clinal," of which the present Alps are " only the eastern half." Suess's syntaxis must also, 
it would seem, be discarded. 

Nevertheless, Hutton's views may be in a general way correct, and the syntaxis of Suess 
may in a modified sense hold good. 

When the position of New Zealand with respect to the Pacific Ocean is considered, and 
biological evidence taken into account, it seems as if a north-east and south-west, or a north 
and south folding must have prevailed from early times. A similarity in curve of outline 
between New Zealand and the eastern shore of Australia, which has been pointed out by 
Hochstettei-, II leads to a like conclusion. 

Folding may have taken place from earh- geological periods }iarallel to this line in areas 
west of the alpine axis, and may even be of older date than the north-west to south-east folding. 
Perhaps the most satisfactory supposition is that it originated in the Jurassic period (though 
it may be older), and continued at intervals possibly until Miocene times. There is no reason 
why the north-west to south-east folding should not have met the other folding in syntaxis, 
not along the present alpine chain as developed in the Mikonui area, but far to the west of it. 
The general north and south strike of the older rocks in north-west Nelson leads one to think 
that possibly the old direction of folding was north and south , or a little east of north to west 
of south, rather than north-east and south-west. A similar direction of flexure perhaps appears 

* " The Geological History of New Zealand," Trans., vol. xxxii, 1899, pp. 159-183. 

t "The Geography of New Zealand," 1905 (by P. Marshall), pp. 12-13. The views here expressed are 
really those of Professor J. W. Gregory, who wrote the introductory chapter. It Li not clear that Marshall 
agrees with him. See also p. 102. 

J " The Face of the Earth," vol. ii (English translation), 1906, p. 142. 

5 " On the Geology of Marlborough and South-east Nelson," G. S. Rep. during 1890-91, vol. xxi, 1892 ; 
"Geological Explorations of the Northern Part of Westland," Mines Report, 1893. C.-3, p. 181. 

II "New Zealand" (English edition), 1867, p. 36. 



37 

in the north-western part of Central Otago, where it seems to meet a north-west to south-east 
folding in syntaxis.* 

Probably at the end of the Cretaceous, or early iu the Tertiary, the main folding axis 
shifted to the east, and mountani- building began along the line of the present alpine chain. 
It is not, however, till towards the end of the Miocene that we find evidence of the formation 
of a dividing range. In the Pliocene, elevation of the Alps continued, but the old mountain- 
range to the west, together with the greater part of the area, consisting of rocks with north- 
west to south-east folding, which lay between the two chains, disappeared beneath the sea. 

The following table summarises the geological record, with special reference to the periods 
and directions of folding that may have prevailed in this part of New Zealand. Bach folding- 
period implies that uphft took place to such an extent that New Zealand formed part of a 
large area, and is supposed to be followed sooner or later by a period of depression. For con- 
venience' sake, the minor upheavals and subsidences during the Tertiary periods are also added. 
The first column gives Button's views, as expressed in his paper of 1899 on the geological 
history of New Zealand ; whilst the second gives the modifications proposed by the writer, 
which seem applicable to the geological history of Westland. 

Folding Periods and Movements of Land. 



Hutton. 



This Bulletin. 



Devonian. — North-east to south-west folding along 
axis to west of Southern Alp.s. 

Carbonijerouji. — Subsidence, and formation of .Maitai 
Series, &c. 

Permian. — Repetition of above folding. (jranite 
erupted along west side of Southern Alps. Pro- 
bable land connection with Australia 

Jurassic. — Great folding, and formation of an im- 
mense chain which included the present Alps as 
its eastern wing. Subsidence to west, and Tasman i 
Sea formed. Jjind-connection with New (Jiiinea ' 

Upper Crelaceovjt. — Subsidence . . 

At end of CreUiceoii.i or Early Eocene. — Last e.Ktenaive 

folding period. Land stretched far to north, but 

was not unitetl with New (luinea 



Oligocene. — Period of depression . . 



h'nd ot Oligocene. — Slight upheaval 
Miocene. — Depression 



Older Pliocene — Exten.iive elevation, and land- surface 
extending far to east and south of New Zealand 

Xexver Pliocene and Pleistocene. — Moderate subsidence 

Late Pleistocene and Recent. — Slight elevation 



Formation of Arahura (upper beds) and Greenland 

ISeries. 
Any N. and S. or N.E. and S.W. folding, well to west 

of area. Possible \.W. and S.E. foldmg. 

Folding along N.W. and S.E. axes over present 
alpine area, and much of Canterbury and Otago. 
Probable strong folding well to west of area, along 
a N.N.E. to S.S.VV. axis, which may have met the 
N.W. and S.E. folding in syntaxis. 

History of area a blank. 

Probable folding along present alpine axis, with 
granite intrusions, &c. .Marlied general elevation, 
with long ensuing period of denudation. 

Eocene. — Deposition of lower beds of Koiterangi 
Series. 

Period of depression (positive movement of the strand- 
line). Deposition of upper beds of Koit«rangi 
Series. 

Probable slight elevation. 

Early Miocene. — Depression(?)- Peneplaination of 
the whole or greater part of the alpine area 
completed. 

Middle J/ iocewe.— Further minor folding and marked 
uplift of Alps. 

Late Miocene. — Depression (probably local). 

Rapid uplift along present alpine axi.^. Advance of 
glaciers. Subsidence to west of old mountains, &c. 
Faulting and warping of area. 

Elevation of Alps probably checked. Iplift of foot- 
hill area(V). Retreat of glaciers during Pleistocene. 

Slight elevation of mountain-chain, kc. Faulting 
and warping. 



* This statement is based on Hutton's account of the geology of this region. 
Otago," 1875, p. 23. 



See " Geology of 



38 



CHAPTER IV. 



PHYSIOGRAPHY. 



General J'eatures 

Mountains and Hills 

(a.) The Main Alpine Divide . . 

(6.) Subsidiary Ranges of the Alpine Chain 

(c.) The Granite and Gneiss Mountains 

(d. ) Outlying Ridges and Hills 

(e.) ^lorainic Hills 

(/.) The Ancient Peneplain 

{g.) Mode of Formation of Alps 

(h.) Structure 

Passes and Saddles 

Plains, River-flats, and River-terraces 

Rivers 

( 1. ) The Hokitika River and its Tributaries 
(2.) The Totara River and its Tributaries 
(3.) The Mikonui River and its Tributaries 
(4.) The Waitaha River and its Tributaries 
(5.) Duffer Creek and various Lowland 

Streams 
(6.) The Wanganui River and its Tribu- 
taries ^ « 



'ase. 




Paee. 


38 


Waterfalls and Cascades 


63 


39 


Gorges 


54 


39 


Grade of Rivers 


54 


39 


Hanging Valleys 


55 


41 


Areas of River- basins 


55 


41 


Volumes of Rivers 


56 


42 


Captured Drainage and Ancient River- 




42 


courses . . 


56 


43 


Glaciers 


58 


43 


Glacial Erosion, Transportation, and De- 




44 


position . . 


60 


46 


Snowfields . . 


61 


47 


Springs 


62 


47 


[a.) Cold 


62 


50 


(b.) ilineral 


62 


51 


Lakes 


63 


51 


Lagoons 


64 




The Shore-line 


65 


52 


Fans 


H6 




Talus 


66 


52 


Slips 


66 



General Features. 

The area under cousideration is one of great geographic interest, presenting, as it does, the 
typical Westland physiography described in the Hokitika Bulletin.* The dominating feature 
is furnished by the Southern Alps, ^vith their snow-clad summits, which, bounding the eastern 
and southern parts of the horizon, reach, near the sources of the Whitcombe and Wanganui 
rivers, a height of between 8,000 ft. and 9,000 ft. In this part of the district are extensive 
snowfields and several large glaciers. Seaward of the main chain are subsidiarv ranges, with 
peaks reaching 6,000 ft. or 7,000 ft., and sometimes more. Towards the coast the mountains 
lessen in height, and on the seaward side of a well-marked ancient valley, of sufficient importance 
to demand the special name of Gregory Valley, drop to heights under 4,000 ft. From the 
glaciers and snowfields large streams take their course. These flow through deep and often 
gorgy channels to the lowlands, where they spread out over wide gravel-beds. The smaller 
streams descend steep, narrow valleys in a series of cascades and waterfalls to the main 
watercourses ; but it is to be noted that many of these minor as well as the major streams in 
their upper portions flow through comparatively wide, open valleys, with steep side-slopes. 
Here and there the larger valleys open out into small flats, terrace- bordered, which at one 
time were probably lakes. As the main streams approach the outer margin of the mountains, 
their valleys become broader, and tuially merge into the low country. The strip of land between 
the mountains and the sea is wholly composed of debris derived from the mountains. The 
surface is partly river-flat or coastal plain, but quite one-half of the lowlands is covered by 
morainic accumulations, which reach a height of over 1,000 ft., and south of the Mikonui 
present long cliff-faces to the waves of the ocean. One lake of some extent — lanthe — a moraine- 
dammed sheet of water, is found in the subdivision. Along the coast are several narrow salt- 
water lagoons, and beyond are the blue ever-restless waters of the stormy Tasman Sea. 



* Bull. Xo. 1 (New Series), N.Z.G.S., 1906, Chap, iv, pp. 24-39. Practically the whole of the general 
physiography of this bulletin applies, mutatis mutandis, to the Mikonui Subdivision. 



•^. 



■JI105S JIM 



•a.iuB[iBH IK 



•no^Sni-jaaji -jjv 



■>lBoa 01JBHS 



•aosj-UBH IIV 



•i.tt!-iBX 



•[laApBaJX ire 







G 



CS 



39 

Mountains and Hills. 
The mountains of the Mikonui Subdivision may be considered under the headings of— 
(a) the main alpine divide and adjoining peaks ; (6) subsidiary rarges of the alpine chain : 
(c) mountains of the granite* and gneiss belt ; (d) the outlying ridges and hills ; (e) morainic 
hills ; (/) the ancient peneplain ; (g) mode of formation of Alps ; (/() structure. 

(«.) The Main Alpine Divide. 
The alpine divide forms the south-eastern boundary of the area under consideration for 
a distance of about thirty-live miles. The actual vvater-partuig follows a rather sinuous 
line, and does not always pass over the highest points. Almost everywhere it is characterized 
by jagged peaks connected by serrate ridges, rather than by rounded dome-shaped moun- 
tains. The most noteworthy peaks are, from north to south. Mount Park (about 6,700 ft.), a 
■bold outstanding mass of rock just to the west of the actual water-parting; Mungo Peak 
(about 6,000 ft.), Mounts Treadwell (6,919 ft.), Bryce (7,177 ft.), Kai-iwi (6,843 ft.), Harrison 
(6,812 ft.), Shafto (6,919 ft.), Ballance (7.008 ft.), Stout (6,962 ft.), Tregear (6,712 ft.), and 
Aryan Ridge (6,289 ft.), the last two being jagged rocky peaks which rise from the eastern 
side of the Upper Hokitika Valley ; Mounts Marion (6,953 ft.). Button (6,536 ft.). Split Open 
(6,706 ft.), Tarleton (6,456 ft.), McWhirter (6,940 ft.), Warner (7,363 ft.). Bond (7,581 ft.). 
Law (7,107 ft.), and Neave (7,530 ft.), on the eastern side of the Whitcombe Vallev : and 
Mount Louper (8,165 ft.), which rises on the south side of Whitcombe Pass. South of the 
Wanganui Saddle rises the noble peak of Mount Whitcombe (8,656 ft.), the highest point 
actually within the area now being described, though Mount Lambert, just outside the southern 
boundary, is probably somewhat higher. 

(6.) Subsidiary Ranges of the Alpine Chain. 

The most northerly of the subsidiary ranges that are now to receive attention is the 
Browning Range, which leaves the main divide near Mount Beals under the name of Wood 
Range. Passing out of the Browning's Pass Survey District, it continues in the Mikonui 
Subdivision as an east and west ridge, which divides the Browning or Styx River from the 
I'pper Kokatahi. The Browning Range is characterized by its serrate crest, with steep slopes 
on either side. Where it enters the subdivision it is about 5,000 ft. in height, but drops going 
westward. 

From Mount Ambrose (6,596 ft.), a peak on the main divide just to the east of the Toaroha 
Survey District, a high ridge separating the headwaters of the Kokatahi and Mungo rivers 
runs westward for .some miles. Prominent points on it are called The Rampart (6,169 ft.), 
and Bastion Ridge (5,946 ft.). .\t Mount Chamberlin (5,928 ft.) it joins the Toaroha Range, 
an exceedingly rugged ridge which starts on the east side of Toaroha Saddle, near the source 
of the Toaroha, and inins almost due north till it ends near the junction of the Toaroha and 
L'pper Kokatahi. The principal peaks are Mounts Bannatyne (5,954 ft.) and Reeves (5,881 ft.), 
and The Pinnacle (4,960 ft.). On the higher parts of the Toaroha Range are permanent snow- 
fields and even small glaciers. 

The Diedrich Range begin.s on the west siSe of Toaroha Saddle, and runs in a general 
northerly direction till it ends against the Koiterangi Plain, between the Toaroha and Hoki- 
tika rivers. The principal heights, in order from north to south, are Mounts Ross (4,790 ft.) ; 
O'Connor (5,957 ft.), a bold rugged mass prominent even when \aewed from Hokitika ; Jumble- 
top (5,290ft.), also visible from Hokitika; and Squall Peak (4,544ft.). At .hmbletop 
several steep, razorbacked spurs strike off from the main ridge. On one of these is Mount 
Diedrich (3,558 ft.), a well-known land-mark and trigonometrical station. 

• Here and elsewhere in this chapter granite is used as a field name, inchiding biotite-granite or 
granitite, hornblende-granitite, && 



40 

Knobby Ridge is an exceedingly jagged, razorback offset ninning almost due west from 
Mount O'Connor towards the Hokitika River, with Mount Robinson (4,580 ft.) as its most 
prominent peak, and terminating in Frew Peak (3,260 ft.), with a well-roimded bushed summit 
in sharp contrast to the rest of the ridge. 

Between Mungo Saddle and Whitcombe Pass the main divide sends off several short ridges 
and spurs to the north and north-west, most of which need not be further described. One 
of these ridges which extends to Frew Saddle may be considered as continuing under the 
name of Meta Ridge to the junction of the Hokitika and Whitcombe rivers. Its principal 
peaks are Mount Meta (5,350 ft.) and Mount Inframeta (4,482 ft.). From Mount Meta a 
short offset known as Conway Ridge, rising to about 5,200 ft., runs towards the Hokitika- 
Mungo junction. 

The Lange Range, which with its branches is quite the most important of the subsidiary 
ranges, leaves the main divide south of Whitcombe Pass, and rxuis almost due north for many 
miles till it reaches the Gregory' Valley. Throughout its whole length it is exceedingly rugged 
and picturesque. Great precipices and narrow razorbacks render many parfs almost inacces- 
sible. Among the higher peaks are Mount Evans (8,612 ft.). Park Dome (7,688 ft.), Mount 
Beaumont (7,035 ft.), and Mount Bowen (6,516 ft.). 

From a point between Mount Evans and Park Dome a high ridge known as Bloomfield 
Range runs west and north-west between the County and Waitaha rivers. The most pro- 
minent heights are Artist Dome (7,061 ft.), a beautifully rounded mountain, and Mount Bloom- 
field (6,885 ft.). Starting south of Mount Beaumont, a ridge, part of which from its serrate 
profile has been named Saw-tooth Ridge, runs westward for many miles. The main part is 
called Hitchin Range, and has as prominent points The Tusk, Ragged Peak (6,804 ft.), and 
Momit Hitchin (5,662 ft.). From Mount Hitchin a narrow spur Kjontinues westward for 
several miles to Urquhart Knob, but the main ridge turns north-west. Beyond Mount Allen 
it drops, and may be regarded as ending. 

Second in magnitude only to the Lange Range, from which it branches oft' at Mount 
Evans, is the Smyth Range, which separates the valleys of the Waitaha and VVanganui rivers. 
It runs almost due west for eight or nine mUes, then swings gradually round, and runs due north 
till it ends against the lowlands. The principal peaks are Red Lion (7,941 ft.), Mount Barry 
(6,838 ft.), Mount Neville (6,582 ft.), Mount Smyth (6,005 ft.), Mount Durward (6,311 ft.), 
and Mount Ashmore (4,845 ft.). 

The southern part of the Wanganui River watershed is even more rugged and inaccessible 
than the northern part. The Lord Range, which is between the Wanganui on the north 
and the Lord and Lambert rivers on the south, though not quite so lofty as some of the other 
ranges just described, is the most magnificent of all. The illustration (Plate XI) gives but a 
faint idea of the remarkable rock sculpture of this range. 

Between the Lord and Lambert rivers is a short range, the most noticeable elevation of 
which is Mount Stoddart, a fine rocky peak with a great precipice on the west or Lambert 
side. - 

From a point somewhat to the south of the last-mentioned ridge, the long range which 
forms the southern boundary of the Wanganui watershed begins. Like the Smyth Range, 
it rims at first west, and then turns to the north, the latter portion being called the Wilberg 
Range. The most conspicuous point is Mount Lambert, a magnificent rocky peak rising to a 
height of 8,500 ft. or more. Towards the head of the Adams, where the range bends round 
to the north, are several other fine mountains crowTied with perpetual snow. The Wilberg 
Range ascends to nearly 6,000 ft., but is practically free from snow towards the end of summer. 
Its most northern summit. Mount Wilberg, is about 4,260 ft. in height, but the point where the 
trigonometrical station has been placed has an altitude of only 3,998 ft. 

Many more or less prominent peaks within the area just described have not been men- 
tioned, either because they are somewhat dwarfed by higher neighbours, or because their 
heights and positions have not been exactly determined. 



41 

(c.) The Granite and Gneiss Mountains. 

The hills and mountains coming under this heading are rather remarkable in being more 
or less isolated both from the other mountains of the area and from one another. They lie 
along a north-east and south-west line, forming a continuation of the granite areas described 
in the Hokitika Bulletin.* 

The most northerly of these isolated masses is Mount Hany, a low wooded hill of rounded 
outline, about 1,000 ft. in height, on the southern side of the Toaroha, near its junction with 
the Kokatahi. A mile or two south-west of Mount Harry is Doughboy Hill, a wooded some- 
what conical hill, with steep sides, which rises to a height of 1,967 ft. It is a well-known 
land-mark, noted by Sir Julius Von Haast in 1865.t 

West of the Hokitika River is Mount Misery (3,050 ft.), a rather prominent hill with its 
summit clothed in alpine scrub. South-west of Mount Misery, between Doctor Creek and Miko- 
nui River, are Fraser Peak and Bald Hill, which reach elevations of 3,822 ft. and 3,802 ft. 
respectively. A short ridge, almost free from scrub, leads from Fraser Peak to the Bald 
Hill Range, along which for nearly two miles there is easy travelling on open grassy country. 

South of the Mikonui River is the Mikonui Sugarloaf, which, as viewed from Gribbeu 
Flat, is a conspicuous hill composed principally of gneissic rocks. Between the Waitaha 
and the Wanganui rivers. Mount Bonar, a beautiful double peak, almost isolated from the 
schist mountains by the modern valleys of Douglas and Evans creeks, rises to a height of 
3,527 ft. 

(f/.) Outlyuig Ridges ami Hills. 

With the exception of Koiterangi, which is partly in other survey districts, practically all 
the outlying hills are found in the Totara Survey District. Koiterangi itself, as viewed from 
the direction of Kokatahi, is a hill with a remarkable outline, which has caused it to receive 
from the European settlers the appropriate name of Camel-back. The hill, vvliich is quite 
isolated, rises abiniptly from the Koiterangi- Kokatahi Plain to a height of 1,841 ft. The initial 
trigonometrical station of the Hokitika meridional circuit has been placed on the highest point, 
whence on a fine day a magnificent view may be obtained. It is easily reached by means 
of a track starting from the road-junction near the foot of the eastern spur. 

Koiterangi was supposed by Von Haast to owe its outlines mainly to glaciation, and 
therefore to be an enormous rocke moutonnee.X The physiographic features and outcrops of 
crushed rock indicate that it is bounded by faults on at least two sides, and, since the coal- 
measures which continue eastward from the mountain under the gravels of the Kokatahi 
Plain, when they meet the older rocks seen in that direction must almost necessarily be cut 
ofE by faults. Koiterangi maybe regarded as an example of a block mountain. (Plate XXII.) 

West of the Hokitika River, between Falls Creek and Doctor Creek, is Doctor Hill, a long 
flat-topped ridge, which rises to a height of 2,360 ft. West of Doctor Hill is Ford Ridge, which 
nms northward from Bald Hill for about six miles. Except at Wilson Saddle, where it drops 
to 1,521ft., Ford Ridge preserves a nearly uniform^'height of 2,000 ft.' to 2,300 ft.** At its 
northern extremity are Constitution Hill (2,071 ft.) and Pigeon Hill (2,033 ft.). 

Between the''^^Totara and Mikonui rivers is Mount Greenland (2,968 ft.), aj steep-sided 
but remarkably even-crested mountaui. Malfroy Spur rims a little east of north from Mount 
Greenland for several miles, and another spur from the mountain runs first north-west and 
then north to near the Mont d'Or Claim. 

South-west of the Mikonui River is the well-known Rangitoto Range, whose rugged slopes 
were once reputed to contain gold- and silver-bearing lodes of great richness. The range has 
three peaks, at no great distances apart, the highest being Moimt Rangitoto (3,695 ft.). From 

• BuU. No. 1 (New Series), N.Z.G.S., 1906, pp. 27, 61-66. 

t " Geology of Canterbury and Westland, 1879, p. 91. 

i ■■ Geology of Canterbury and Weatland," 1879, pp. 91 and 224. 



42 

its summit the view obtained of the lowland country and the Southern Alps is one of the 
finest in Westland. 

Between the Kakapotahi and Waitaha valleys is Purcell Ridge, which, beginning near 
Mount Allen with'a height of nearly 2,000 ft., gradually drops" to a few hundred feet. It is 
fairly even-topped, but on both east and west sides it descends steeply into the neighbouring 
river- valleys, the western drop being particularly abrupt. This, together with the almost 
straight Une presented by the base of the ridge, suggests a fault. 

(e.) Morainic Hills. 

A very large portion of the lowland country is covered by ice-borne material, which rises 
in places to hills over 1,000 ft. in height. Very pR)minent is Bold Head, or Waitaha Blufi. 
an isolated hill facing the sea between the mouths of the Mikonui and Waitaha rivers. It is 
apparently the terminal moraine of the ancient Waitaha Glacier, and attains a height of over 
400 ft. 

Whaleback Hill, west of Duffer Creek, is a long, high morainic ridge, very noticeable 
from the top of Mount Rangitoto. West and north of Lake lanthe are great masses of morainic 
debris rising to a height of at least 1,095 ft., or over 1,000 ft. above the lake. These extend to 
the sea-coast, and for miles present high cliffs to the ocean. The high ridge near the Wanganui 
River is known as the Bunker Hills. These huge piles of debris — the Bunker Hills, Whaleback 
Hill, and other similar though smaller mounds — have been deposited by a great glacier, which 
formerly came down the valley of the Wanganui River and reached into the sea beyond the 
present coast-Hne. 

(/.) The Ancient Peneplain. 

In the Hokitika Bulletin detailed reference was made to an elevated peneplain — the 
Wainihinihi peneplain — which is apparent over at least the greater part of the alpine area in 
the Hokitika Subdivision.* In the Mikonui area peneplaination is less clearly indicated, on 
account of the greater complications introduced by faulting and wai'ping, as well as the dis- 
guising effect due to unequal erosion. Nevertheless, a marked uniformity in the peaks of the 
alpine divide is noticeable, and on reaching the crest of the range this feature is found to be 
well developed on the Canterbury side, where for many miles eastward the peaks reach almost 
the same elevations. On the Westland side, however, the moimtains drop towards the sea 
in a more or less indistinct step-like way, the final drop of 2,000 ft. or 3,000 ft. suggesting a 
huge fault. Along lines parallel to the main axis the summits are fairly uniform, though 
there is in the Mikonui Subdivision a distinct rise in the general height of the alpine chain 
from north to south, which, outside the subdivision, is continued southward till it culminates 
in the magnificent mass of Mount Cook, rearing its crest 12,.349 ft. above sea-level. It may 
therefore be concluded that the alpine chain as seen in North Westland is part of an ancient 
peneplain or an old land-surface, eroded to a base-level, or almost so, which has been uplifted 
by mountain-building movements to its present position. 

Westward the ancient peneplain is down-faulted and shrouded by the old coastal plain 
except in the foothill area between Koiterangi Hill and Mount Rangitoto. Here the flat 
tops exhibited by most of the hills, together with the fairly uniform drop from north to south, 
indicate an ancient base-level of erosion, which, it would seem, was continuous with the Wai- 
nihinihi peneplain. The foothill area appears to have been tilted during its uplift, and 
is, as previously mentioned, considerably faulted. Since its elevation it has evidently 
been subjected to a c^'cle of erosion of a complicated nature. 

In the Hokitika Bulletin the Wainihinihi peneplain was stated to be of post-Koiterangi 
age.t An Early Miocene age, as assigned in Chapter III, is perhaps the most probable. 
Although at present there is little dii'ect evidence in favour of the supposition that the ancient 

♦ Bull. No. 1 (New Series), N.Z.G.S., 1906, pp. 24, 26-27. f Loc. cit., p. 26. 



PLATE XI. 








\lK\V FKO.M W'aNC ANUI I' UliKS TO HeAU Of \VAN(iANU[ YaI.LKY. MoUNT WhITCOMBE (8,656 FT.) OK 

iiii;iiT OK MICH Saddi.i: ; Muei-i-eu Peak (G, 643 ft.) on extuem.i^ right. 



t 




-1 


i 


ii^B^fe'ni ^'>r''i ^i"!!! 




^^^^^^^^^^h|^^^H 




^n^ji^^^B^^m 






m 



I'llK I.UKI. liA.M.j-. A> .-i-.t.N 1-1<0.\1 \Va-\(.A.NL1 i''ui{K.->. Till. i'i.AK OX THE EXTREME LEFT IS 

Mueller Peak. 



acul. Bull. Xo. C.l 



I'To face pai/c .^J. 



43 

peneplained surface of the Southern Alps was contemporary and continuous with the Otago 
peneplain described by Marshall,* Park.t and others, yet the hypothesis is quite tenable. 
It may be noted that Park points out that there are no marine strata of Eocene age known in 
New Zealand, and suggests that the Otago peneplain originated during the Eocene. He 
apparently considers that it may have persisted to the latter part of the Miocene.J It is 
not improbable also that the North Westland peneplain was contmuous with the ancient 
Nelson peneplain, incidentally mentioned by Gregory in the mtroductory chapter of 
Marshall's " Geography of New Zealand " (page 9). 

ig.) Mode of Formation of Alps. 
The Southern Alps are made up almost wholly of intensely plicated sedimentary rocks, 
and therefore form a typical folded chain, modelled on the general principles that apply to all 
the major mountain-chains of the world. Owing to the divergent views held by geologists 
and earth physicists concerning the exact mode in which these great winkles arise on the 
earth's surface, it is not possible to state with certainty every step of the processes of moun- 
tain-building as it took place in the Southern Alps. If one adopts in a general way the views 
of Suess, it would appear that the folds forming the Southern Alps as seen in the Mikonui area 
were produced by a force acting on the neighbouring parts of the earth's crust towards the 
north-west. According to the principles enunciated by this famous geologist, a great over- 
thrust fault might be looked for on the western side of the Alps. Field evidence shows that 
a great fault, or series of faults, here exists, whilst the presence of a line of granite bosses along 
the western margin of the Alps is highly suggestive of a cicatrised wound in the earth's crust. 
It may be concluded, then, that the uplift of the Southern Alps was largely the product of 
folding, accompanied by a bodily forward movement of the folds up the inclined plane of an 
overthrust fault. There is, however, a third possible factor to be taken into account — direct 
uplift of a difierent character to that produced by the tangential forces which give rise to 
folding. The existence of tension faults is in conformity with the ^^ew that the Southern 
Alps are in part the result of a vertical or nearly vertical uplift, which took place during the 
latter stages of their formation. More precisely, it is thought that the Alps have been sub- 
jected to at least two main uplifts. The first was produced by or during an intense folding of 
the strata, and was followed by a long-continued period of erosion, which resulted in pene- 
plaination of the old range. The second uplift^ — that which has produced the modern range — 
was probably accompanied by minor folding only. 

(h.) Stmcture. 

(1.) The Southern Alps. — As already indicated, the folds of the Southern Alps on the 
Westland side of the mahi di\ade trend from north-east to south-west. The strike varies 
from nearly north and south to nearly east and west, but for the most part approximates to 
a bearing of 225°. On the western side several complete major folds may be traced, together 
with a number of more or less local crumplings. Little detailed work has yet been done on 
the Canterbury side, but it is known that the strike, though generally south-west and north- 
east, is often erratic, and the folds are numerous. § It ma}' be said that even the major 
flexures can hardly be exactly defined or enumerated, because in the course of a few miles 
the anticlinal part of a given fold appears either completely to subside, a syncline taking 
its place, or else the fold breaks up into minor plications. 

* " The Geography of New Zealand," 1905, pp. 5, 102, 106. 

t " The Geology of the Area covered by the Alexandra Sheet," BulL No. 2 (New Serie.s), N.Z.G.S., 1906, 
p. 6 ; also " The Geology of the Cromwell Subdivision," Bull. No. 5 (New Series), N.Z.G.S., 1908, p. 7. 

i Loc. cit. (Bull. No" 5), p. 7. 

§ Von Haast, " Geologj' of Canterbury and Westland," 1879. p. 274. In the part of Canterbury referred 
to, the influence of the older south-east to north-west folding may still be traced in spite of the younger 
alpine folding, which, west of the main divide, has almost entirely obliterated it. Some Palaozoic rooks in 
Banks Peninsula, according to Von Haast, have the older strike {he. cit., p. 263). 



44 

Where no recent disturbance has taken place, the strata invariably dip at high angles, 
often approaching 90°. Near the main divide the folds are overturned in places ; but there is 
no evidence of overfolding on a large scale, except towards the western margin, where there 
are probably several isoclinal folds with an easterly dip. 

The folds are arranged in such a way that as one passes from west to east younger and 
younger beds become exposed. The structure has been compared to that of a huge anticlino- 
rium, of which the western half has been removed by denudation or subsidence. So Hoch- 
stetter. Von Haast, and, following their lead, other writers have regarded it,* but such is 
hardly the case. As indicated below, the grauwackes and argillites of the western foothills 
are not only less intensely folded than the rocks of the al])ine area, but strike in a direction 
almost at right angles to the trend of the Southern Alps. The former rocks approach, but 
are nowhere seen actually in contact with, the gneissic schists of the outer granitic belt, which 
generally have the alpine strike. From these they are always separated either by granite or 
by a low-lying belt of debris-covered country, usually of no great width. 

It is clear that the supposed western \\'ing of the great anticline or anticlinorium ha.« 
never existed, at least in Westlaud, north of Mount Cook : for in that case the presence imme- 
diately to the west of rocks of the same age as some of those composing the Southern Alps, 
but with totally different strike, would be impossible. 

(2.) The (rrairite-yneiss Mountains.— In the general description attention was drawn to 
the complete or partial isolation of the mountains in the granite-gneiss belt, a condition brought 
about by longitudinal and transverse valleys. The granite masses of these mountains are 
bosses, from which in places dykes are given off into the neighbouring rocks. 

The gneissic schists that flank the granite in Mount Misery, Fraser Peak, &c., on the 
east or inner side of the belt, generally strike east-north-east and west-south-west, and dip 
eastward. South of Fraser Peak the strike is irregular, though the dip is constantly near 90°. 
On the outer or western side of the granite Ijosses the strike and dip of the gneissic schists 
are very irregular. 

(3.) The Foothills. — About two-thirds of the area covered by the foothills consists of 
Palaeozoic grauwackes and argillites (Greenland Series). These are strongly folded along 
north-west and south-easr lines. The dip is verv coinmonlv about 60°, but varies from 30° 
to 90°. In general the anticlines are worn down into river-\alleys, whilst the synclines form 
the higher hills, such as Mount Greenland and Constitution Hill. The grauwackes of the 
Rangitoto Range, however, are arranged anticlinally. In this case the highest point and 
more than half the \dsible surface of the range itself are composed of granite. 

The remainder of the foothills consists almost wholly of granite, the intrusive character 
of which into the Palaeozoic rocks is verv clearlv shown by the altered character of the grau- 
wacke near the granite, by the presence of granitic dykes in the grauwacke in several locaUties, 
and by numerous grauwacke inclusions. 

Passes and Saddles. 

(1.) Passes over the Main Divide. — The chief saddles on the main divide are : Mmigo 
Saddle (5,9.o0ft.); Mathias Pass (4,700 ft.); Kea Pass (about .5,700 ft.). near the head of 
Vincent Creek; and Whitcombe Pass (4,025ft.). Two of the saddles — namely, Mathias 
Pass and Whitcombe Pass — are free from snow for a considerable period of the year, and 
are occasionally traversed by prospectors and others. The tracks on the Westland side to 
these passes have already been described (page 21). The more northern pass, the Mathias, 
is a narrow saddle, now approached with some difficulty from the Canterbury side, the benched 
track which once existed ha\diig been partly destroyed by slips just where it leads romid a 

* Hochstetter, " New Zealand " (English edition), 1867, p. 489 ; Von Haast, " Geology of Canterbury and 
Westland," 1879, p. 242y£see also Button, " The Geological History of New Zealand," Trans., vol. xxxii, 
1899, p. 161 ; and Marshall, " Geography of New Zealand," 1905, p. 98. 



45 

precipitous face. Whitcombe Pass is a fairly broad saddle, with a gradual ascent on either side, 
which would form a practicable route for a coach-road. (See Plates II and III.) 

Muiigo Saddle, near which the Alps enter the subdivision, is a narrow col adjoining 
Mount Park. It is easily reached on the Westland side from the valley of Brunswick Creek, a 
branch of the Mungo River. On the Canterbnrv' side there is a steep, and at times difficult, 
descent over snow and rocks into the valley of the Gibson, a tributary of the Wilberforce 
River. In the summer of 1905-6 this pass was not quite free from snow,* but in February, 
1907, the saddle itself and the neighbouring parts of the main divide were bare, though snow 
lay in the depressions on either side. About the beginning of April the snow on the Westland 
side had almost disappeared. 

Kea Pass, at the head of Vincent Creek, can be reached without much difficulty from 
the Wliitcombe Valley. The descent on the Canterbury side appears to be rather difficult. 

(2.) Saddles of the Subsidiary Ranges. — The subsidiary ranges are often remarkably even- 
topped, and though there are, of course, many minor notches, the number of depressions 
which may be called saddles is surprisingly few. Among the more noteworthv are Toaroha, 
Frew, Meta, Zit, and Sm^•th saddles. 

The Toaroha Saddle is situated at the head of the Toaroha River, between Mounts Banna- 
tyne and Ross, and leads into the valley of the Mungo. It is a grassy ridge 3.840 ft. in height 
at its lowest point, easily ascended from the Toaroha, but having a steep slope of nearly 
1,500 ft. on the Mungo side. Owing to the general straightness of the Toaroha Valley, the 
saddle, with the exception of its lowest notch, can be seen from Kokatahi and other points 
ou the lowlands. 

Frew Saddle, situated at the head of Frew Creek, is easily reached from the Whitcombe 
Valley by means of the track to Mathias Pass, which passes over it into the valley of the 
Hokitika. On the Hokitika side the drop is only a few hundred feet. It is a well-marked 
grassy saddle, having its lowest point 4,267 ft. above the sea-level. 

Meta Saddle, between Mounts M^ta and Inframeta, is a bush-covered depression about 
3.000 ft. in height. It may be reached from the Whitcombe Valley by several routes, but 
on the east side there is a rather steep drop into a nearly inaccessible part of the Hokitika 
Valley, so that the saddle can never be of any use for means of commxmication. 

Zit Saddle, at the head of Zit Creek, leads from the Toaroha Valley into the head of the 
Kokatahi. It is about 4,.'00ft. in height, and apparently can be approached without diffi- 
culty from the small flat near the source of the latter stream. 

Smvth Saddle, at the head of Smvth Stream. leads from the valley of the Wanganui into 
the upper part of the County River. It is a long ridge, which for the most part is razorbacked. 
aiid very difficult of access from either side. A'point on the eastern part of this ridge, which 
was reached \vithout much trouble from the Wanganui by following the Smyth Valley, is about 
5.500 ft. high. 

(3.) Saddles of the Ancient Gregory Valley. — The Gregory Valley is marked out by a series 
of low saddles, which generally afford easy routes from one river-valley into another. 

The most northern of these saddles, that behind Mount Harry, is little higher than the 
upper portion of the Kokatahi-Koiterangi Plain. It leads from the Toaroha River to the 
vicinity of Lake Arthur. The valley behind Doughboy HiU is so low as to be practically part 
of the Kokatahi-Koiterangi Plain. 

Murray Saddle, west of the Hokitika River, forms an easy route into the valley of Doctor 
(Jreek. It is a wide, flat depression, covered by stream-gravels, with a steep ascent of about 
400 ft. or 500 ft. from the Hokitika. 

Douglas Saddle, 1,540 ft. above sea-level, at the head of Doctor Creek, leads into the 
Mikonui Valley, and is very similar to Murray Saddle. 

• Hull. No. 1 (New Series), N.Z.G.S.. 1906, p. 38. 



46 

Truraii Pass leads from the Tnke Valley into Pollock Creek, a tributary of the Kaka- 
potahi. It is similar to Douglas and Murray •iaddles in being almost flat for some distance, 
and in being covered by recent deposits, but is narrower. 

Evans Saddle is a low ridge, with a height probably under 1,000 ft., separating the upper 
valleys of Douglas Stream and Evans Creek. 

(4.) Saddles of the Foothills. — The Dip is a low. wide, and flat saddle, covered by recent 
deposits, which Ues between Doctor Hill and Ford Range. It forms the water-divide between 
Falls Creek and the valley of Doctor Creek, and is about 800 ft. above sea-level. 

Totara Saddle, near the head of the Totara River, is only 750 ft. above sea-level at the 
highest point of the track which leads over it into the Upper Mikonxii Valley, and. like The Dip, 
has a surface-covering of stream-gravels. 

The wide, gently imdulating saddle which separates the llikonui and Kakapotahi rivers 
south of Mount Rangitoto has no general name. There are several minor saddles on it, one 
of which, at the head of Red Granite Creek, is called Xorthcroft Saddle, and another, separating 
Be van and Slate creeks, has been named Mair Saddle. The main saddle, which is from 1,800 ft. 
to 2,000 ft. in height, is in places covered by more or less recent deposits, and is thought to 
have once formed part of an ancient river-valley. 

Plains, River-flats, and River-terraces. 

One of the largest areas of flat land in Westland is furnished by the Koiterangi-Kokatahi 
Plain, of which about one-sixth Ues in the Toaroha Survey District. This part of the plain, 
except for a small area of swamp, consists of fertile, well-drained land, with a gentle seaward 
slope of about 25 ft. to the mile. The height above sea-level varies from 150 ft. near Koiterangi 
Hill to 250 ft. towards the foot of the mountains. Outside the subdivision it continues as 
the lower valley of the Hokitika till it finally coalesces with the modern coastal plain. 

The Koiterangi-Kokatahi Plain has been built up of gravel, sand, and silt brought down 
by the Hokitika River and the various branches of tke Kokatahi. This material has been 
deposited in a depression, apparently formed mainly by faulting, of which there is considerable 
evidence. It is possible that ice may have aided in shaping this hollow, but the ^•iew that it 
was excavated solely by ancient glacial action is not well supported by field study. 

The Waitaha Plain is another large area of flat land, about eight miles in length, with 
an average width, including river-bed, of nearly two miles. East and west it is boimded by 
steep scarps, which appear to be fault -lines, but may possibly have been produced by ice erosion. 
These continue as morainic ridges, which curve round and almost meet at the north end of 
the plain where the river has been bridged. E%'idently the valley, after the retreat of the glacier 
which once occupied it. became a lake, which was gradually filled by the deposits of the Wai- 
taha River. 

Within the subdivision there is a third considerable river-flat stretching between Lake 
lanthe and the Wanganui. This area comprises but a small portion of a comparatively large 
plain, of which the m.ajor part is on the south side of the Wanganui. Like the Koiterangi- 
Kokatahi Plain and the Waitaha Valley, it represents an old filled-up post-glacial lake. The 
soil of the portion \vithin the subdivision is fertile, but not a little consists of swampy land. 

From the Totara River to Te Raho-Taiepa Stream there is a strip of modern coastal 
plain foirteen miles in length, but nowhere of any great -width. It is -widest south-west 
of the Mikonui, but here the greater part is swamp. 

There are various areas of flat land throughout the lowlands which either occur on top of 
the flu\'io-marine terraces bordering the modern coastal plain, or form the fairly level summits of 
the fluvio-glacial terraces which cover or fringe much of the area occupied by glacial debris. 

The lower courses of the Totara, Mikonui, and Waitaha rivers are bordered by river- 
flats, which merge into the recent coastal plain. In the case of the Wanganui, there is on the 
east bank, about one to four miles from the moiith, a rather large flat isolated by the morainic 



PLATE XII. 




•■•tW* 



Sk-: 



\ii:\v I i;()M W am;.\nli Fouks it L.\Mni;itT Hivicit Vam.ioy. Moukt SjoDiJAid i.\ uackcuound to 

HKiiiT ; Ia)hij 1van(;e on lekt. 




\'li:\V KHUM LOUO ItAXliK OF THK LaMHEKT (il.ACIEU AND MoUNT LaMHEKT. 

Xnti' steep descent of glaciei- aii<l i)recipice intenui^ting its continuity. 
I'liiilo l)ij f.dnilx (111(1 Siirrci/ JJc/Mrti/iciit , J/a/.i/ikd.l 
t,'o/. Hull. Xo. /;.] 



[T(-> fact; pdije Jfli. 



47 

hills and the river. It is, however, really a portion of the Wauganui Plain, a strip of which 
extends down the west hank of the Wanganui to the mouth of the river. 

Where the various rivers issue from the mountains there are narrow flats extending some 
distance up the valleys. Further up the streams are many flats of various sizes, all of which 
occupy rock-basins, and. after the retreat of the glaciers which once occupied and in some 
cases partly excavated them, must, m most cases, have been lakes until filled up by the river- 
gravels. The high gravel-terraces which border all these flats show that they were once filled 
to a higher level, but have been lowered as the river cut down the roclry- lip of the basin. Some 
geologists would ascribe these rock-basms wholly to glacial action, undoubtedly a vera causa 
in some mstances, butreasons will be given on a later page for considerably modifying such views. 

The river-flats are naturally long in proportion to their width. Some in the lower parts 
of the mountain-valleys are of considerable size, and have been taken up by settlers. 

Rivers. 

The rivers of the Mikonui Subdivision, on account of the nearness of the main divide 
to the coast, are short and rapid. Owing to the heavy rain- and snow-fall they carry very 
large volumes of water in proportion to the size of their watersheds. Many of the rivers have 
glacier sources, from which they flow as muddy, turbulent streams through valleys which 
may be fairly wade at first, but presently close in, and at intervals exhibit rock-bound gorges, 
which are often deep and almost always impassable at water-level. Here and there occur 
the small flats to which reference has already been made. Near the lowlands the valleys broaden 
and the grades of the rivers lessen. Finally the rivers emerge on the lowlands, and, splitting 
into numerous branches, which reunite and reseparate, spread out over wide gravelly beds. 
The grades decrease more and more towards the mouth, but the rivers never become really 
navigable, even for small boats, except at the very mouth. 

Owing to their being snow-fed. the chief streams are much larger in summer and early 
autumn than at other seasons of the year. They are liable to heavy floods during any part 
of the year, and are often unfordable for weeks at a time. 

It is evident that the main river-valleys of the area originated as stream-channels, but 
were subsequently modified in shape by ice-action, fxlacial topography is still plainly visible 
in the upper portions of the valleys, but in the lower portions stream erosion has taken place 
to such an extent since the retreat of the glaciers that the signs of glaciation have in a great 
measure disappeared. 

The principal rivers of the area are the Holdtika and the Wanganui, which have their 
sources in the alpine divide, whilst the Waitaha and the Mikonui are also fairly large streams 
which drain outer portions of the main range. The only other streams which have independent 
channels to the sea are the Totara River and a few small watercourses — DufEer Creek being 
the largest — which drain the lowland country south of the Waitaha River. The various 
river-svstoms will now be considered in order from north to south. 

( 1 . ) The Hokitika River and its Tributaries. — The largest stream in the Mikonui Subdivision is 
the Hokitika, which has by far the greater part of its watershed within the area. The headwaters 
of the Styx and to some extent of the Kokatahi, as well as the lower twelve or fourteen miles of 
the main stream, are outside the subdivision, and have been described in the Hokitika Bulletin.* 

Unfortunately, the chief branch of the Hokitika, instead of receiving the name of the 
main stream, has been called the Whitcombe. The error has been repeated with the tributary 
now caUed the Hokitika, the chief branch being the Mmigo and the so-called Hokitika little 
more than a mountain torrent, descending from a hanging valley. Even so late as 1879 Von 
Haast used the name Hokitika for the present Whitcombe. t It is much to be desired that his 
lead should be followed, and the strictly correct name adopted, as would no doubt have been 
the case had Whitcombe survived to publish the result of his explorations. 

* Bull. No. 1 (New Series), N.Z.G.S., 1906, pp. 30, 31. 
■j- " Geology of Canterbury and Westland," 1879, p. 222, 



48 

The so-called Whitcombe may be considered to have its source in the Sale Glacier, which 
descends just on the Westland side of the Whitcombe Pass. The stream from the Sale Glacier 
flows north-west for a short distance, ai\d then, turning to the north into the main valley, which 
is wide and open, is joined by a little creek coming from the pass. A mile or so down fairly large 
streams, fed by the Park and Barron crlaciers, come in from the west. A little lower several 
other creeks entei', mostly from the main divide on the east side of the river. Four miles from 
the pass the Whitcombe. already a large stream, is joined from the west by the Wilkinson, a 
stream of equal size, biit no great length, draining the Wilkinson and McKenzie glaciers. 
After being joined by Bond and other large creeks, the Whitcombe enters a deep, rock-en- 
cumbered gorge, near the north end of which the Price River, a large stream draining part of the 
Lange Eange. flows into the main river. A striking scene is here presented by the foaming river 
and the dark, vertical walls of the Barron Canyon, which has been carved out by the Price. 
A little further on the river reaches Price Flat, which is rather more than half a mile long and 
about a quarter of a mile wide. Here it is entered by Cataract Creek, which rises near Mounts 
Tarleton and Split-open, and has an open, rather flat upper valley, but a steep descent of 
1,600 ft. in less than a mile to the Whitcombe. Below Price Flat is a small gorge, and for 
over two miles the Whitcombe Hows through a dee]j narrow vaUey, with almost continuous 
rock blufis on the western side. Below this the valley opens out, and there is a succession 
of flats bordered by high terrace gravels for about three miles. In this stretch the Whitcombe 
is joined from the west by the Cropp River, a large stream draining the slopes of Mounts Beau- 
mont and Bowen, and from the east by Vincent and Frew creeks. A mile below Frew Creek 
the river passes through Collier Gorge. The actual gorge is short ; but on the east side of the 
river is a long, high blufE, over which a narrow foot -track has been benched. A mile lower 
down the Hokitika comes from the east, and gives its name to the united stream. If at this 
point one looks back, it is seen that the Hokitika is less than half the size of the Whitcombe, 
which runs in a much broader and more mature valley than the Hokitika. The latter stream is 
for many miles nothing but a succession of gorges, audit is easy to believe that the so-called Hoki- 
tika was originally a small stream, that, by rapidly deepening its channel, siicceeded in capturing 
the Mungo, which at one time probably passed over Toaroha Saddle into the Toaroha River. 

From the Hokitika- Whitcombe junction the united stream flows northward through a wide 
valley, an extension of the Whitcombe Valley, and is bordered by a succession of flats and 
gravel terraces, \vith only one rock blufi. Six miles below the junction the river enters a beau- 
tiful gorge over half a mile long, through which it flows as a tranquil, narrow, but deep stream. 
The granite walls of the gorge are from 30 ft. to 60 ft. high. The depth of the channel when 
the river is low varies from 10 ft. to 30 ft. The bottom, so far as could be judged from the 
soundings taken, is, except at the head, ever^nvhere covered with sand or gravel. Emerging 
from the gorge the river enters the Koiterangi-Kokatahi Plain, spreads out into a maze of 
channels, and, flowing aroimd the west side of Koiterangi HiU, leaves the subdivision. 

The Mungo River, the chief tributary of the Upper Hokitika, begins as a glacial stream a 
little south of Moimt Ambrose, a peak on the main di\ide. It flows west through a fairly 
straight, rather open valley, and is presently joined from the south by Park Stream, and from 
the north by Brunswick and Sir Robert creeks, all snow-fed streams. After passing through 
several gorges it is joined by the Hokitika. a much smaller stream than its affluent. 

The Hokitika, as it appears on the maps, has its source in a small snow-slope to the south- 
west of Mathias Pass. After flowing for a short distance to the north-east it turns near Mathias 
Pass to the west of north. It now flows through a rather open valley with glacial topography, 
and is joined on either side by the waters of numerous small creeks and springs. Near Frew 
Saddle the stream bends to the east of north, and for about two miles nins through a narrow 
tussocky flat bordered by steep ridges, from which a few small tributaries descend. The stream, 
turning to due north, presently enters a shallow gorge cut in the floor of the still open valley. 
Soon it reaches the valley of the Mimgo, and, dropping nearly 1,400 ft. in a series of steep 
cascades and small falls, reaches the Mungo with all the characteristics of a juvenile stream. 



49 

Below the Mungo junction the united stream still runs westward, but at Frisco Canyon 
turns more to the north. From here to the Whitcombe junction the Holdtika runs in a pro- 
foundly deep valley, forcing its way through a succession of ^vildly beautiful, impassable 
gorges, with perpendicular walls hundreds of feet in height. 

The largest of the Wliitcombe's many tributaries, the Cropp River, deserves some mention. 
The headwaters consist of a number of small streams draining the snow-slopes of Momit 
Beaumont, The Rotmida, and Galena Ridge. These unite near the foot of Beaumont, forming 
a stream of some size, which flows eastward for two or three miles through a fairly broad, 
somewhat U-shaped valley, containing small gravel flats. The valley then becomes more 
V-shaped, and the stream-bed assumes a much steeper grade. It is full of great boulders of ser- 
pentine and schist, which block the way and render progress along the stream difficult. Finally 
the river enters a profomid gorge, from wliich it emerges into the Whitcombe River valley. For 
the last half-mile of its course the stream, broadening out and anastomosing, traverses a gently 
sloping river-flat. 

The changes of grade observed in the Cropp River are very striking, and are typical of 
many streams within the subdivision. They are graphically illustrated by the lower figure 
of the following diagram : — 




- 6" 20c - 

— Crop p River 



— DIAGRAM — 

Showing profiles of Waitaha and Cro pp Rivers 

SCALES - — 

H0RI20NTM. VERTICftL 
^ O I 2 Mitft "IT '.^M O 



■! — Mikonui. 



50 

The Price River, which also drains part of the Lange Range, has somewhat similar grades 
to the Cropp. The same statement applies to Vincent Creek, which rises near Kea Pass, on the 
main divide, and flows through a wide glaciated valley for some miles, till, nearing the Whit- 
combe, it plunges down with many falls and cascades, probably dropping nearly 2,000 ft. 
in little over a mile. 

The largest tributary of the Lower Hokitika is the Kokatahi, which leaves the subdivision 
a few miles above the jimction, but has most of its watershed within the area now being 
described. While still traversing the Koiterangi-Kokatahi Plain, it splits into three branches, 
each of which has an independent valley among the mountains. 

The Styx or Browning River, the most northerly of these branches, rises outside the 
subdivision, and flows along its northern boundary in a nearly east and west direction through 
a wide, open valley, which has been modified by glacial activity. A branch, or more correctly 
a distributary, of the old Arahura G-lacier once passed through it.* 

The Kokatahi, the middle and largest branch, begins in a number of small snow-fed 
streams which drain a large cirque occupying the angle between the Toaroha Range and 
Bastion Ridge, near Mount Chamberlin. After passing through a little flat, the stream runs 
north and east for several miles through a rather wide valley. In this part of its course it is 
joined by several streams coming from the main alpine divide. It passes outside the subdivision 
for about two miles, but, after being joined at the head of a small flat by the Crawford, a 
large stream coming from the north-east, it turns to the north-west and re-enters the sub- 
division. It occupies a narrow valley for several miles, then, bending north and again west 
in a great curve, enters a deep, wild canyon, named the Whakarira Gorge, through which it 
flows for several miles. From the lower end of the gorge it has a course somewhat north of 
west, and flows in a valley of some wadth, containing narrow flats and high gravel terraces, 
until it emerges on the lowlands. 

The southern branch of the Kokatahi, the Toaroha, has its sources near Mount Bannatyne 
and the Toaroha Saddle, and has a general northerly direction, though with many bends, 
throughout its whole course. A mile and a half from the saddle it flows through a small 
gravel flat, and a short distance lower down descends in a remarkable cascade for over a quarter 
of a mile. The stream-bed is filled with huge boulders, over which progress, especially to 
one burdened with a pack, is extremely difficult. After being joined by Crystal Creek, a 
large snow-fed stream coming from the slopes of Mount Chamberlin, the river, though some- 
what gorgy, is much more easily followed. The next noticeable tributary is Mullins Creek, 
which drains the eastern part of Mount O'Connor, and descends from a hanging valley in a series 
of extremely beautiful falls. After being joined by Jumble, Zit, and Median creeks, the 
Toaroha, now a stream of some size, passes through a beautiful little gorge. Just below this 
gorge Wren Creek, a small stream coming from the mountain-slopes to the north-east, joins 
on the right. Wren Creek is noteworthy on accoimt of the hot spring a short distance above 
the junction with the Toaroha. After flowing through a small flat, the river turns to the left 
and enters a rock-bound gorge — the Toaroha Canyon. For three-quarters of a mile the stream, 
confined to a narrow channel between beetling precipices, dashes wildly around and over 
huge boulders, which vainly seek to impede its course. Again, turning to the north, the 
river, though often rock-bound, becomes more gentle in its grade. The valley now opens out, 
and gravel terraces appear, the most noticeable being Howitt Terrace, which presents a face of 
coarsely stratified material about 300 ft. in height. Finally the stream enters the lowlands, 
and joins the Kokatahi just below the Browning junction. A diagram showing the 
varying grades of the Toaroha River is given on page 159. 

(2.) The Totara River and its Tributaries. — South of the Hokitika River the next stream 
of any consequence is the Totara River, which rises on the slopes of the Bald Hill Range, and 



* Von Haast : " Geology of Canterbury and Westland," 1879, p. 223. Bull. No. 1 (New Series), N.Z.G.S., 
J 906, p- 31. 



51 

follows a general northerly course for about ten or twelve miles until it reaches the Totara 
Lagoon, just outside the north-west corner of the subdivision. The principal affluents on 
the east are Sm>th, Weir, Beaufils, and McKay creeks ; on the west, Cedar, Monteith, Ciilder 
DuiTer. Cameron, McKenzie, and Fox creeks, all descending from the slopes of Mount Green- 
land and Malfroy Range. After reaching the modern coastal plain the Totara is joined by 
Donnelly Creek, a stream of some size,- which rises on the northern slopes of Mount Greenland. 
The Totara is the one river of the subdivision which is not partly snow-fed the whole year 
round. Bald Hill, the highest point in its watershed, reaches only to 3,802 ft. 

(3.) The Mikonui River and its Tributaries.— T\ie Mikonui, a much larger stream than 
the Totara, rises on the north-west slope of Mount Bowen. After a steep gorgy descent of 
about three miles, it enters the ancient Gregory Valley, and runs south-west for about two 
miles. It is then joined by the Dickson River, a large gorgy stream having its headwaters 
towards Mount Bowen and Remarkable Peak. The river entering Gribben Flat now flows 
west-north-west for about five miles. Its principal tributary during this part of its course 
is the Tuke, a stream considerably larger than the Mikonui itself, but contained in a much 
narrower valley. From Gribben Flat the Mikonui passes into the rock-bound gorge four 
or five miles long wliich separates Mounts Greenland and Rangitoto. Here it is joined by 
numerous small streams, the chief of which is Bullock Creek, rising near the summit of Rangi- 
toto. Below the gorge the valley turns to the northward and expands. Finally the river 
enters the modern coastal plain, and reaches the sea about three miles west of Ross. 

The Tuke River, the main branch of the Mikonui, has its headwaters towards The 
Tusk, a peak of the Hitchin Range. After being joined by streams from the neighbourhood 
of Mount Beaumont and from Dickie Spur, and mak-ing a peculiar pot-hook bend, it flows 
somewhat west of north for a mile or two. It then passes through a deep gorge, and, turning 
to almost due north, enters a narrow flat. It leaves the flat by another gorge, and finally joins 
the M konui River near Gribben's. 

(4.) The Waifaha River and its Tributaries. — The Waitaha River, a stream about twice 
the size of the Mikonui, has its headwaters in a deep valley on the west side of the Lange 
Range, a mile or two north of Park Dome. The actual source is a very small glacier, but the 
water from this is joined within the next few hundred yards by two large streams, one from 
the north and the other from the south. These streams come doMTi in waterfalls and cascades 
from two clifE glaciers, the waterfalls and clifi glacier on the north being particularly fine. 
The Waitaha, already of some size, now runs north-west for over a mile through a U-shaped 
valley, in the floor of which it has excavated a small gorge. Towards the lower end there 
is a waterfall of 80 ft., below which the river turns to the south-west for nearly a mile. In 
this reach a large tributary, the Watson joins it from the north, and another, the Reid, drain- 
ing the northern slopes of Arti.st Dome and the neighbouring ridge, comes from the south. 
Below Reid Stream the Waitaha, turning north-westward, runs through a small terraced flat. 
For two or three miles the valley is wide and open, the grade of the stream is moderate ; then 
the valley closes in a little, and the river, gently curving to the south-west, descends steeply, 
falling 800 ft. in a distance of three-quarters of a mile. After being joined by Chainman 
Stream from the north-west it turns due south, and plunges into an inaccessible gorge, with 
precipices from 400 ft. to 800 ft. high on either side. The grade is still steep, and in about 
three-quarters of a mile the drop is 700 ft. As the Waitaha emerges from the gorge proper 
it is joined from the south-east by a very large stream, the County. From this junction the 
Waitaha flow.s, on the whole, almost due west for about five miles. For some distance there are 
numerous blufl[s on the north bank, then comes a succession of gorges. A mile below *the 
County Stream junction, Bruce Stream, draining the northern slope of Mounts Barry and 
Neville, comes from the east of south into the Waitaha. Three miles further on, the river, 
after emerging into a flat of some width and nearly a mile in length, is joined by Kensington 
River, a stream draining the northern slopes of Mounts Smyth and Durward. Below the flat 
the river enters the last gorge, and, sharply curving to the north, emerges into the gradually 
4' — Mikonui. 



52 

widening valley which contains the Waitaha Plain. From this point to the sea, the river, 
spreading out over a wide shingle-bed, maintains a northerly direction. Just below the Main 
South Eoad Bridge it is joined by the Kakapotahi or Little Waitaha, its last tributary of any 
size. 

The upper figure on page 49 represents diagrammatically the changes of grade in the 
Waitaha River from its source to the lowlands. 

The County River has its source in a glacier of some size, which descends from the slopes 
of Red Lion and Artist Dome. The river, which is noticeably muddy, first flows west, but soon 
turns and maintains a north-west course through a U-shaped valley till it reaches the Waitaha. 
The last mile or more of its channel is characterized by an extremely steep grade and a bed 
filled with immense boulders. This condition — a boulder-filled bed with steep grade — has 
already been noted in the Toaroha, Cropp, and Waitaha rivers. It is a rather common 
phase of Westland streams at elevations between 1,500 ft. and 3,000 ft., and often succeeds 
a U-shaped valley of moderate grade. 

The Kakapotahi River originates in a number of creeks draining the western slopes of 
Dickie Spur and the neighbouring part of the Hitchin Range. These unite in a deep valley, 
forming a stream which flows north through a gorge, and, entering the flat known as Happy 
Valley, bends to the north-west. Here it is joined by Pollock, Hitchin, and other streams. 
Leaving the flat, it passes through a succession of beautiful granite gorges (Plate XIII). After 
emerging from the gorges, it flows throiigh a narrow valley cut in morainic and fluvio-glacial 
gravels imtil it reaches the Waitaha. Though there are permanent patches of snow near 
the Kakapotahi sources, there are no momitains of sufficient height to support glaciers, in 
consequence of which its waters are always clear, except during flood-time. 

(5.) Duffer Creek and various Lowland Streams. — Duffer Creek originates on the northern 
slopes of Mount Bonar, and, after flowing north for about three miles, emerges on the low- 
lands. It traverses morainic and fluvio-glacial country to within a short distance of the 
sea, when it reaches the modern coastal plain. The creek empties into a long, very narrow 
lagoon, called Duffer or Omiatai Lagoon. 

The Raho-Taiepa is a stream of some size, though hardly a river, which has its head- 
waters wholly within the glacial gravels between DufEer Creek and the Wanganui River. It 
discharges into the south end of the Ounatai Lagoon. 

Other streams entering the Ounatai Lagoon are Alexander, Allen, and Milwain creeks. 
North of the Wanganui Bluff, Waikoikoi Creek drains a valley with some flat land which 
the stream has cut in the glacial accumidations. 

(6.) The Wanganui River and its Tributaries. — The Wanganui River, an important stream 
about twice the size of the Waitaha, and in summer not much smaller than the Hokitika, 
drains the southern part of the Mikonui Subdivision and a considerable area outside the sub- 
division to the south. Some description of this part of the watershed will, however, be here 
given. 

The Wanganui River has its source in the Evans Glacier, and flows in a general south 
of west direction for about ten miles. A mile below the Evans Glacier it is joined on the 
south by the Vane, and half a mile further on Smyth Stream enters from the north. A little 
below the Smyth the grade becomes steep for about a mile. The bed is here encumbered with 
great boulders, and a high precipice forms the northern bank. During the next few miles 
several streams, including the Waller and the Fairfax, flow into the river. There are several 
bluffs along this part of the river, but no gorges. About nine miles from its source the 
Wanganui emerges into a flat of some size. Here, after being joined by the Lambert, a larger 
stream than itself, which drains a considerable area of high coimtry to the south, it turns to 
a little north of Avest. The principal streams flowing into the Wanganui for the next six miles 
are Hende Creek, Hot Springs Creek, and Wilberg Stream. There are several rock bluffs in 
this part of the river, but for the greater part of the way small flats and terraces of moderate 
height border the stream, which is easily followed except at the bluffs, and at one or two 



PLATE XIII. 




<il!.\MTK (ioltCK OK IvAKAl'OTAlll li'lVKI!, Sl'ANNKIi HY JiOC KoOTUl! 1 1)1 : 10. 
('iiIitlMst willi views (111 Pbitr XXI. 




Gkoi.ocicai. SuiiVKY Cami', m:ai! HoKiTiKA (;oi!<;i:. 



Gvol. Bull. No. 6'.] 



\_Tu face iniijc 



53 

places where large ice-transported boulders make the travelling bad. At Canopy Bluff the 
river turns to the north, and from here to Hende's, two miles lower down, where it emerges 
on the lowlands, is bordered on either side by flats or low terraces. Stege Creek is the only 
affluent of any size in this section. Opposite Hende's is a good ford, generally negotiable in 
fair weather by vehicles or horsemen during summer, and in winter easily crossed by pedes- 
trians, though the coldness of the water makes fording on foot by no means a pleasant experience 
at any season of the year. From Hende's to the sea, a distance of about fourteen miles, the 
Wanganui, still flowing in a general northerly direction, anastomoses over a wide shingle- 
bed. On the west bank there is a river-flat all the way, but on the east the river runs against 
morainic hills at two places, one about six miles, and the other about a mile from the mouth. 
The only tributaries of any importance in this portion are Evans and lanthe creeks on the 
east and La Fontaine or Petersen Stream on the west. 

In a sense the Wanganui is navigable for a boat or canoe from the sea to some miles above 
Hende's — that is to say, a boat could be taken up by " traclcing," whilst the descent in boat 
or canoe would be easy, though in .some of the upper reaches more than a little exciting. 

The open character of the Wanganui Valley is in marked contrast to that of the other 
rivers of the Mikonui area, the Whitcombe- Lower Hokitika Valley excepted. The Wanganui 
Valley is, however, easier to explore than the Wliitcombe Valley, owing to the absence of 
gorges. In summer several bluffs have to be surmounted by climbing, but can be avoided 
in winter, when the river is low. by fording. (See Plates XI and XIX.) 

The Vane begins on the slopes of Mount Lord as a small stream. It cascades down over 
bare rock-faces into a deep, narrow gully, where it presently disappears under a glacier of 
some size — the Essex — which, coming from the main divide to the east, completely fills the 
valley for about half a mile. From the terminal face of this glacier a large stream issues, 
and joins the Wanganui after flowing a mile in a southerly direction. The existence above 
the ice-lobe of a deep V valley, which has evidently been produced by stream erosion, is a 
peculiar feature not easily explained. It may be that the Essex Glacier, through some physical 
change near the main divide, has recently advanced into the Vane Valley. 

Smvth Stream has its principal source in a small glacier descending from Mount Barry. 
After being joined by Bradshaw Creek it passes through a short gorge, and for a short distance 
runs in a rather flat and ojien valley. The grade soon steepens, and for nearly a mile the 
stream descends over huge boulders on a grade of about 1 in 4. At the foot of this remarkable 
reach it enters the Wanganui. There are no waterfalls, and the ascent from the river below 
is surprisingly easy. 

The Lambert flows northward from the beautiful Lambert Glacier, and after an extremely 
gorgy course of three or four miles reaches the Wanganui. It has two large tributaries— the 
Lord and the Adams, the former joining about two miles below the Lambert Glacier, and 
the Adams near the Wanganui junction. 

The Lord River is merely a short stream which flows for two or three miles in a westerly 
direction from the Lord Glacier. Its valley, though rather broad, owing to recent glaciation, 
is deep, and the high precipices which border it on either side render it all but inaccessible. 

The Adams River takes its rise in a valley glacier of no great size, and flows in a general 
north-east direction for five or six miles imtil it joins the Lambert. Its valley is consider- 
ably more open than that of the latter stream. Its unusual direction at right angles to the 
ordinary drainage of the alpine chain deserves attention. 

Waterfalls and Cascades. 
The major streams of the Mikonui Subdivision run in well-developed valleys, and in con- 
se<,uence there are hardlv any large waterfalls. In certain parts of almost every river, how- 
ever, particularly where gorges occur, many rapids or cascades of noticeably steep grade appear, 
and 'sudden drops of a few feet are fre.juent. On the other hand, the smaller streams are 



51 

characterized b)- many waterfalls and steep cascades, particularly towards their heads and 
near the junctions with the main streams. 

The only waterfalls to be found in a major stream- valley within the alpine area are the 
two which occur towards the head of the Waitaha River. One of these is an 80 ft. or 100 ft. 
drop, about a mile and a half from the head of the river. Its formation is due to a change in 
the bed-rock from soft, crushed material to a hard and tough rock. The second fall is just 
below the junction of Chaiimian Stream, where the Waitaha plunges into a deep gorge. Here 
there is a sudden drop of at least 20 ft. or 30 ft., but it is difficult to get a complete view of 
the fall, and the height may be greater than that stated. 

The Upper Hokitika, before joining the Mungo, descends nearly 1,400 ft. in a series of 
cascades and falls ; but, as remarked on page 47, the so-called Hokitika is here really a 
minor stream, tributary to the Mungo. 

In the granite gorges of the Kakapotahi Rirer are several small falls, which give evidence 
of comparatively recent uplift in the foothill area. 

The principal rapids in the larger streams are those of the Toaroha, above Crystal Creek, 
and in the Toaroha Canyon ; of the Waitaha River, above and below its junction with Chain- 
man Stream ; and of the Upper Wanganui River, about half a mile to a mile below the Smyth 
Stream junction. 

It would take up too much space to enumerate the falls and cascades of the minor streams, 
but those of MulUns Creek, a tributary of the Toaroha, may be mentioned as being very beautiful 
as well as of great height. 

Gorges. 

Many of the canyons in the main river-valleys have already been mentioned in the de- 
scriptions given of the river-systems. Gorges are e\*en more abundant in the minor stream- 
valleys, and many of the smaller creeks run through gorges for almost their whole length. 

The comparative youth of the present cycle of erosion is, of course, the prevailing factor 
in the formation of the gorges. The more immediate causes of their formation may be stated 
as follows ; (1) Bands of harder rock alternating with soft material, which in many cases 
consists of rock crushed by fault-movements ; (2) recent uplift and warping. 

Grade of Rivers. 

In the lowland country the grade of the main rivers varies from a few feet per mile near 
the sea to about 20 ft. per mile as the mountains are approached. For the next few miles 
the usual grade is from 30 ft. to 60 ft. per mile ; it then increases to 100 ft. per mile or more, 
especially in the gorges. Towards the head, where rapids come in, the grade may be from 
200 ft. to 500 ft. per mile, and in some cases quite 1,000 ft. per mile — as, for example, in the 
Waitaha River above the County River junction. In the case of the Whitcombe, which has per- 
haps the most fully d3yeloped valley in the area, the grade of the reach of four miles below 
the Wilkinson junction is about 200 ft. per mile, and above the junction considerably nlore. 
The Upper Wanganui, also with a well-developed valley, has even steeper grades, one portion 
approaching 800 ft. per mile. 

The varying grades of the rivers in the mountain areas cannot always easily be explained. 
In many cases, as mentioned in the next chapter, it seems to be due to recent warping and 
uplift. A probable explanation in those instances where the river-valley above a steep grade 
is U-shaped depends upon glacial action. When a glacier paused in its retreat up a river- valley 
there would be little excavation towards the front of the glacier, though corrasion would 
doubtless be vigorous a mile or two higher up. Thus a reduction in the grade of the valley 
for a greater or less distance would take place. On the other hand, the valley for half a mile 
or more below the glacier would be partlv protected from erosion by the larger boulders of the 
terminal moraine, and would tend to acquire a steep grade, owing to stream excavation in 
the reach below. 



55 

Hanging Valleys. 

The minor streams very commonlj^ exhibit hanging valleys — that is, they descend in 
cascades and waterfalls to the main watercourse, while above they run in a comparatively 
flat valley for some distance. Very often the difference of level between the main and tributary 
valleys is from 1,000 ft. to 2,000 ft. In such cases the upper valley is almost always U-shaped, 
and clearly moulded by glacial action, whilst in many instances its head is still occupied by 
a small glacier. (See Plate VI.) 

Faulting as a primary cause may be dismissed, though it is probably responsible in some 
cases, directly or indirectly, for part of the discrepancy in level between the main and the 
hanging valleys. Warping and tilting are also quite minor agents. The primary cause is 
therefore unequal erosion, due apparently to the main stream cutting its valley at a much greater 
rate than the tributar}' one ; but the question of stream erosion is complicated by the intro- 
duction of glacial excavation. 

E. C. Andrews, in an able paper, has referred the hanging valleys observed by him in 
Southern New Zealand to the greater erosion caused by the main ice-streams, as compared 
with the minor glaciers of the side-valleys.* His explanation, however, cannot be well applied 
to the hanging valleys of the Mikoimi Subdivision, because the main valley is in all cases, 
apparentlv mainly stream, and not ice, eroded. Though this appearance of stream erosion 
is to some extent deceptive, for glaciers have in past times occupied all the larger valleys, 
one must at present suppose that, on the whole, difierential stream erosion has been the main 
cause of the production of hanging valleys in the subdivision. It would seem that in many 
cases the small glaciers which occupied the hanging valleys to a late date protected them 
to a great extent from being cut down, especially towards their lips. 

Before leaving the subject it ought to be mentioned that the Pliocene uplift of the alpine 
range would greatly increase the grade, and therefore the cutting-power of the main streams. 
whilst their tributaries would be relatively much less affected.f 



Areas of River-basins. 
Owing to the nearness of the main divide to the coast, none of the rivers possess 
large watersheds. The following table of approximate watershed areas used in conjunc- 
tion with the table of volumes of rivers gives a means of computing the probable annual 
precipitation, or, the precipitation being known, will enable one to calculate the average 
volumes : — 



Hokitika — 

Whole river 

Above junction with Kokatahi 

Above junction with Whitcombe 
Kokatahi — 

Whole river 

Main branch 
Browning . . 
Toaroha — 

Whole river 

Above Toaroha Canyon . . 
Whitcombe 



Area of 
Watershed in 
Square Miles. 


. . 445-9 


. . 206.6 


430 


. . 1350 


390 


250 


280 


190 


. . 840 



Proceedings 



* •• Some interesting Facts concerning the Glaciation of South-western New Zealand." 
of the Australasian Society for the Advancement of Science, vol. x, 1905, pp. 189-20o. . ,, . , , 

t In this connection see K. .J. Garwood : '• On the Origin of some Hanging Valleys in tiie Alps and 
Himalayaa, ■ Q.J.G.S., vol. Iviii, 1902, p. 70ti, &c. 



56 



Mikonui — 

Whole river 

Above first gorge 
Waitaha — 

Whole river 

Above first gorge 
Kakapotahi — 

Whole river 

Above first gorge 
Wanganui — 

Whole river 

Above Lambert junction 
Lambert (including Lord and Adams) 









Area of 
Watershed in 
Square Miles. 




594 








40-7 








. 130-2 








444 








37-2 








280 








1911 








344 








44-3 



Volumes of Rivers. 

During the course of field-work in the Mikonui Subdivision the larger streams were re- 
peatedly gau'ged whenever opportunity offered. Owing to the absence of bridges, it was 
usually necessary to find a spot where the stream could be forded. Cross-sections were then 
obtained by measuring the width and depth of the stream at suitable intervals, and the surface- 
velocities determined by means of floats. In some cases the conditions were very unfavourable 
for obtaining good results ; still, most of the figures here submitted may be considered as 
reliable as could be expected from the rather rough methods necessarily employed. Almost 
all the measurements were made when the streams were fairly low. Since in shallow, stony 
streams the mean surface-velocity is likely to exceed the true mean velocity, in most cases 
from 25 to 33| per cent, was deducted from the calculated result in order to allow for 
this and the other sources of error, such as that arising from the presence of large 
boulders, &c. 

The table facing this page gives the results of all the measurements, reduced as above, 
together with the estimated minimum flow in fine weather. 



Captured Drainage and Ancient Eiver-courses. 

Captured Drainage. — When the last main uplift of the alpine chain began in Pliocene 
times, many of the present river- valleys had probably taken shape. The streams they con- 
tained were, however, not independent watercourses, but (it is thought) tributaries of a large 
river which ran from south-west to north-east, nearly parallel to the present coast-line, and 
drained high land to the west as well as to the east. Since this Pliocene river was in existence 
great changes have taken place in the land-surface. The high land to the westward has dis- 
appeared beneath the ocean, the Alps have been further uplifted, and glaciers have advanced 
to the sea and retreated to the higher parts of the mountains. Naturally considerable changes 
have also taken place in the drainage-system of the Mikonui Subdivision. Not only has the 
great Pliocene river disappeared, but some of the mountain-streams have considerably in- 
creased the area of their watersheds, whilst others have correspondingly lost. The lowland 
drainage is, of course, altogether modern. 

The most noticeable example in the area of a stream which has gained by capturing other 
drainage is the Hokitika River from the Whitcombe junction upwards, which, as mentioned 
on a former page, starting as a small stream has captured the Mungo, a river formerly draining 
into the Toaroha Valley. Numerous slips near the Toaroha Saddle testify that capture of the 
Toaroha watershed is still going on. Capture by the Hokitika of the Whitcombe watershed 
along Meta and Conway ridges is indicated in a similar way. The Upper Hokitika above the 
Mungo junction seems once to have passed over Frew Saddle into the Whitcombe. Possibly 



57 



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58 

glacial erosion removed a dividing ridge, and enabled the Mungo to capture the headwaters 
of the I'pper Hokitika. 

The present Mikonui River probably owes its importance solely to the capture of the 
headwaters of the ancient Totara, which once extended into the vallev of the Tuke. The 
diversion of drainage was probably aided by the deposition of glacial debris on the Totara 
Saddle, which, even now, is only 750 ft. in height. 

On a minor scale capture on one side with corresponding loss on the other is continually 
taking place to a noticeable extent along the higher water-partings of the area. In some cases 
the losses and gains are fairly evenly balanced, but in others the gain is all on one side. 

The changes noted above in the drainage-channels, and others which have taken place 
in the area, have been caused mainly by ordinary river erosion, though glacier corrasion and 
damming by ice probably assisted to some extent. Uneven uplift may have been a factor of 
great importance not only in. Pliocene, but also in pre- Pliocene times. 

Ancient River-courses. — What may have been a tributary valley to that of the great 
Pliocene river already mentioned is evidenced by the wide, nearly flat saddle south of Mount 
Rangitoto, which is continued northward by the Totara Saddle and the present valley of 
the Totara. The Upper Kakapotahi forms an extension of this supposed ancient river- 
valley. 

Coarse river-gravels found on Purcell Ridge (at an elevation of nearly 2,000 ft.), on Douglas 
Saddle (1,540 ft.), and on Murray Saddle (about 900 ft.) may indicate a stream of later date 
which flowed north-east through the ancient Gregory Valley to the valley of the present Hokitika, 
but there are considerable difficulties in the way of accepting this view. 

Probably the valley of Doctor Creek was formerlv occupied by a larger stream than the 
present one, and a stream of some size once passed through the wide valley between Doctor 
Hill and Ford Ridge, as is shown by river-gravels which cover The Dip. It seems likely 
that drainage from outside areas was temporarily diverted through these valleys by ice- 
damming during the time of the glacial extension. The same explanation may apply to 
the gravels mentioned in the last paragraph. 

From the eastern slopes of Mount Bowen an old channel of Vincent Creek is plainly 
visible on the eastern side of the Whitcombe Valley. This channel runs northward of the 
present gorgy portion of the Vincent Creek Valley towards the mouth of Frew Creek. 
Through the glacier or post-glacial wideiung and deepening of the Whitcombe Valley, the 
ancient valley of Vincent Creek was tapped, and the stream enabled to take a more direct 
course to the main river. 

Glaciees. 

The area now being described contains a large number of glaciers, some of considerable 
size, and though none, except perhaps the Wilkinson, can claim to be of the first order, many 
are of great beauty and interest. 

Taking the more interesting or larger glaciers as far as possible in order of the river- 
valleys from north to south, the first to come under notice is at the head of the Mungo. The 
length of the glacier proper is under a mile, and the width about 100 to 200 yards. At the 
head is a snow-slope extending to the summit of Mount Ambrose. On the west side of the 
Mungo Glacier is a beautiful Uttle cUfE glacier. 

Park Stream has its source in a glacier which, fed by the snow-slopes of Bastion Ridge 
and The Rampart, descends to within 3,000 ft. of sea-level. 

The Stout Glacier descends from the main divide near Shafto Peak for a considerable 
distance into the valley of Sir Robert Creek. This glacier is of some size, but was not closely 
examined by the Geological Survey, owing to its being in a position difficult of access. 

There are several notable glaciers in the valley of the Whitcombe. The Sale Glacier 
descends near Whitcombe Pass from the slopes of Mount Louper. It possesses a rather steep 
surface grade, and so far as could be seen lies in a poorly developed valley which appears to 



59 

overhang the pass. At the time of the writer's visit very little of the glacier could be seen 
through rain and fog, but its width is not less than 300 yards. Its length is probably some- 
what over a mile. It has formed a large terminal moraine, a considerable part of which is 
on the Canterbury side of the Whitcombe Pass,* and thus indicates that the glacier once 
descended more to the south-east. 

Lower down the Whitcombe Valley the Park and Barron glaciers, fed by the snow-slopes 
of Mount Louper and the ridges to the north, descend to within a short distance of the Whit- 
combe River, where they almost meet. Owing to the adverse weather conditions at the time 
the head of the Whitcombe was surveyed, Uttle can be said concerning these glaciers. They 
are small ice-streams of steep grade, and their valleys, if any, are poorly developed. Thev 
have deposited a good deal of morainic material, and appear to have formerly joined forces 
and extended down the Whitcombe \'alley for some distance, leaving behind them, when they 
retreated, a considerable amount of morainic debris. 

The Wilkinson Glacier, though not of extraordinary size, is one of the finest glaciers 
in the Southern Alps. It descends to the north-east from the Bracken Snowfield as an ice- 
fall or cascade of exquisite beauty, to which the illustration (Plate XIV), though a good photo- 
graph, quite fails to do justice. To the south of the ice-fall is an enormous precipice, probablv 
exceeding 1,500 ft. in height, and capped by 100 ft. or 200 ft. of well- stratified neve. Over 
this precipice avalanches, the largest of which may be seen and heard many miles away, 
freiiuentlv thunder, especially during wet weather. The lower part of the glacier is about 
half a mile wide and three-quarters of a mile or more in length. It terminates partly against 
a high terminal moraine, partly as an ice-cliff over 100 ft. high. At the latter point the foot 
of the glacier is 3,040 ft. above sea-level. The face of the ice-cliff shows numerous well- 
marked layers, some fairly clear, others dirty, separated by layers of dust. A large muddy 
stream issues from a low cave in the ice front, and joins the stream coming from the McKenzie 
Glacier. Great blocks of ice frequentlv fall from the cliff, rendering the passage along its front 
extremely dangerous, and in ])iaces pncunil)ering the stream to such an extent that the water 
can hardly be seen. 

There is a great deal of moraine on the lower part of the glacier, but the surface of the 
part near the ice- fall itself is free from debris. 

A fine view of the Wilkinson Glacier can be obtained from the Whitcombe Valley, near 
the junction of the Whitcombe and Wilkinson rivers. A good though distant view may also 
be obtained from the summit of the Meta Kange. 

A short distance above the Wilkinson Glacier is the McKenzie Glacier, which descends 
from the northern slopes of Moutit Evans on a rather steep grade, and has a width of about 
300 yards. At its head is a lofty col leading into the valley of County River. Its foot is 
3,365 ft. above sea-level. On its northern side is an immense precipice, which is crowned 
by two fine cliff glaciers fed from the slopes of Park Dome. The McKenzie Glacier has given 
rise to a considerable terminal moraine, which partlv hides its front, and extends down the 
valley as far as the Wilkinson Glacier. 

The Count V Glacier, at the head of County River, is fed from the south by the snow-slopes 
of the Red Lion and Mount Evans, but derives its greatest supply of ice from Artist Dome 
and other mountains to the north. The glacier flows first westward, and then gently curves 
round to the south of west. The length of the glacier proper appears to be somewhat under 
two miles, and its width about a quarter of a mile. There is a great deal of morahie on 
the lower part of the glacier, which has an easy grade, and could be traversed without 
difficulty. 

The Evans Glacier, at the head of the Wanganui, has a length of about two and a half 
miles, with a width of 350 to 500 yards, and descends from the Bracken Snowfield with an 
average slope of over 12° to within 3,680 ft. of sea-level. It exhibits well-marked indications 



See also Von Haast : " Geology of Canterbury and Westland," 1879, p. 127. 



60 

of having retreated and shrunk in dimensions in recent times. When the glacier was ascended 
at the end of February, 1908, to within a short distance of the point where it merges into 
the Bracken Snowfield, the lower part was found to have a slope of 8° or 9°, and was covered 
with moraine to such an extent that the ice was only occasionally seen. About three-quarters 
of a mile from the foot the moraine began to lessen, and soon disappeared altogether. Crevasses 
from 1 ft. to 6 ft., and even 15 ft. to 20 ft. wide were fairly common ; but these were easily 
passed, till one of great size, and stretching from side to side of the glacier, prev^ented further 
progress, when an elevation of nearly 6,000 ft. had been attained. 

A remarkable feature of the Evans Glacier is furnished by the ice-carved precipices which 
border either side from the foot to within a short distance of the neve. It was owing to these 
that the survey party was unable to pass the great crevasse mentioned above. On the north 
side the precipice merges into a great sloping rock-face, partly covered by large patches of 
snow and ice, which give rise to frequent avalanches. 

About a mile and a half above the foot of the glacier a small tributary glacier descends 
the steep slope on the north side. Its own surface and that of the main glacier at the junction 
are much serac-ed and broken. 

The Essex Glacier, as already mentioned, descends from near the main divide through an 
apparently shallow lip into the valley of Vane Stream, which it completely blocks for nearly 
half a mile. The part visible from the lower extremity is of steep grade and extremely broken, 
forming an ice-cascade of considerable beauty. It is a curious circumstance that this glacier, 
which furnishes at least three-fourths of the water in the Vane Stream, has not been able to 
excavate a valley at all comparable in maturitv or depth to that of the upper part of the 
Vane (see also page .53). 

The Lord Glacier steeply descends from the main divide south-we.st of Mount Lord into 
an inaccessible valley bounded on either side by high precipices. 

The Lambert Glacier, like the Lord, flows steeply downward from the main divide. It 
is fed by the snow-slopes of Mount Lambert and the adjoining peaks. About a mile from 
its head it is broken by a remarkable precipice, the visible part of which is 500 ft. or 600 ft. 
high, over which it descends in frequent avalanches. From the foot of the precipice the 
reconstructed glacier continues for a short distance in a valley, the sides of which are vertical 
for considerable heights. 

The Adams Glacier, at the head of the Adams River, as seen from a distance appears to 
be a small valley glacier of the ordinarv tvpe. 

Glacial Erosion, Transportation, and Deposition. 

When one views the extraordinary raorainic deposits of the lowlands, the great trans- 
porting powers of glaciers are at once apparent, and a natural impulse arises to attribute to them 
equally great erosive powers. Even though the conclusion be correct, the implied reasoning 
is faulty, for the material deposited by the glaciers is coarse debris which has been dislodged 
from the rugged mountain-ridges by frost and other weathering agencies, to be received by the 
glaciers and by them transported to the lowlands in a manner impossible to running water. 
It cannot, therefore, be regarded as a measure of true glacier erosion. In the area under 
consideration the phenomena of ice erosion observed appear somewhat contradictory. 

The view has lately been strongly advanced that glacial erosion is due largely to the 
action of the subglacial streams. This opinion has much to recommend it. Indirectly the 
transporting-power of glaciers must assist subglacial stream erosion, because all the large 
stones and boulders which would encumber the bed of an ordinary river are speedily removed. 

Whatever may be the real facts of glacial erosion, its effects on a large scale are not par- 
ticularly evident in the Mikonui Subdivision, notwithstanding its recent glaciation. In the 
mountains the lower parts of the main valleys have all the characteristics of river-valleys 
(Plate XV), without any easily detectable signs of glacial excavation. It is only at their 



PLATE XIV 




VlKW 1)1 \\ lLKl.\.-i.i.\ \ Al.l.KY, .-llUWlXi. J KitMl-NAI, Moii.M.XK VV W ILKLS^OS (jLACiJil!, AVITU MoUNT 
EvANr< IX BACKOROUNU, AND McKkNZIE CoL ON RKJHT. 

Cloud hitlc'S smiiiiiit i>t' inoiiiitaiu. Conipaio witli Plate V. 




ViKW Ul- \Vll.Kl-N>-O.N Gl.ACIKK, SHOWIXU IcK-FALL AND PhECIPICES. 



Gtul. Bull. So. li.] 



\To fare paijt 00. 



I'LATK XV 




View fijom Side of Kaxge near Cataract Creek up Whitcombe Valley towards AVhitcombe 

Pass. Mount Louper on right of Pass. 

Modified j^lacial topograpliy is developed towai'ds head of valley, hut is not apparent 

in lower portion. 




View from near Frew Saddle down Valleys of Frew Creek and Whitcombe IJiver. 

Mount Bowen (6,51Gft.) in distance. 

Note that valleys do not show glacial chaiacters. 

Gcul. Bull. Xu. 0.] [Tu fare [Kiijc 01. 



61 

heads that one may find a U-shaped valley of undoubted glacial origin. Many of the smaller 
streams also have U-shaped valleys towards their sources. 

In a few cases the formation of shallow rock -basins excavated by ice is very apparent. The 
lips have usually been quite cut down by stream-action, but in one or two instances a gravel 
Hat gives proof of an existing rock- basin. 

The lower river- valleys must have been filled with ice during the glacial advance, and the 
absence of glacial topography is a little surprising. Two or three possible explanations may 
be advanced— one is that the subglacial streams, finding a steep V-shaped valley, continued to 
deepen it in the same way ; another, perhaps more feasible, is that the river-valley was filled 
to a considerable depth with almost inert ice. Over this layer the whole work of the glacier 
was performed. The view that the river-valleys are wholly subsequent to the glaciers cannot 
be entertained, but there can be little doubt that since the retreat of the glaciers ordinarj, 
stream and subaerial erosion frequently much assisted by the soft or shattered nature of the 
strata, has to a great extent destroyed the U-shape once possessed by the lower portions of the 
valleys. In places, morainic debris, old river-gravels, and talus-accumulations assist in 
shrouding the ancient glacial troughs. 

It is likely that in the Mikonui Subdivision ice erosion was not sufFicientlv prolonged to 
result in mature glacial topography, .so that when the glaciers receded to the upper portions 
of the valleys the lower portions were still capable of being deepened by stream-action. It 
is thought too, that further elevation of the Alps may have resulted in a partial rejuvenation 
of stream-action. 

Snowfields. 

At the present day there are few large snowfields in the Mikonui Subdivision, for though 
much of the high country is above the permanent snow-line, many of the peaks are so jagged 
and steep that they aiiord little lodgment for snow. In a bygone age the case was very dif- 
ferent, and it is not difficult to imaghie that at a period when the erosion of the valleys and 
canyons had not reached its present extent, one great snowfield covered almost the whole 
surface of the alpine chain, and fed huge glaciers extending to the shore-hne, and even into 
the sea itself. 

The largest snowfield in the subdivision, called the Bracken, in honour of one of New 
Zealand's truest poets, is situated near the alpine divide south-west of the Whitcombe Pass. 
It occupies a considerable area of nearly flat or somewhat gently sloping country, averaging 
about 7,000 ft. in height, with occasional rocky peaks and ridges of over 8,000 ft. The natural 
section seen at the top of the high clifl west of the Wilkinson Glacier shows that the snowfield 
is at lea.st 100 ft. to 200 ft. in thickness. The Bracken Snowfield feeds the Wilkinson Glacier in 
the Whitcombe watershed, together with the Evans Glacier at the head of the Wanganui, 
and mav be considered to extend over the alpine divide, where it connects with the snow- 
fields feeding the Ramsay Glacier, an ice-stream of the first rank, which forms the source of 
the main branch of the Rakaia. 

There is a snowfield of some size to the north of Mount Evans, which feeds the McKenzie 
and in part the County glaciers. 

On the long, flat top of Mount Beaumont and on the neighbouring slopes is a snowfield 
which gives r'se to several small glaciers in the valleys of the Price and Cropp rivers. 

A small snowfield, which shows the influence of slope in the production of a pern^anent 
snowfield, is found on a gentle slope extending eastward from the summit of Mount Bowen 
(6,516 ft.). Deep crevasses show that the mass is at least 100 ft. thick in places, and has a 
downward movement. On the other hand, the steep slopes on the north and west of the 
same mountain are practically free from snow at the end of an ordinary summer. 

There are many other snowfields in the subdivision, but none is of great size towards 
the end of the summer season, w^hen they are to a great extent separated from one another by 
rocky ridges and deep valleys. Most of these are indicated on the accompanying maps, though 



62 

in many cases it has been found impracticable to delineate the boundaries with anv great 
accuracy. 

Springs. 

The springs found within the Mikonui iSubdivision belong to two classes — (a) Cold springs 
fed by surface waters ; (6) mineral springs. Except one, all the known springs belonging to the 
latter class are warm, with temperatures ranging from about 90° Fahr. to 160° Fahr. 

(a.) Cold Springs fed by Surface Waters. — These are extremely abundant at the foot of the 
talus slopes which abound in the upper river-valleys. Those which supply the main part 
of the water flowing in Brunswick Creek are worthy of particular note. Half a mile above the 
junction of this stream with the Mungo there are two large springs on the south-west side of 
the stream, whilst a quarter of a mile higher up five streams of water gush from the talus 
slope on the east side of the creek. One of these springs furnishes nearly half the water running 
in the creek. Similar springs abound towards the heads of the Hokitika, Whitcombe, and 
many other rivers in the area. 

Where the rock composing the mountains is somewhat broken, it is a common occurrence 
to see large springs gushing out of the rock-faces and formnig the sources of considerable 
creeks. 

The numerous cold springs of the area fulfil a function of some importance in maintain- 
ing the river-volumes during periods of minimum surface supply — for instance, during the 
winter season. 

(b.) Mineral Springs. — Mineral springs occur in six or seven locahties in the subdivision. 
Their presence is in all cases easily detected by a smell of sulphuretted hydrogen and by a 
deposit of white, thread-like silica, due to the action of algae. Without exception the mineral 
springs issue not from solid rock, but from terrace or fan gravels, and in almost every instance 
are close to the edge of a stream. In practically all cases there is more or less independent 
evidence afforded by the topography, or shattered rock in the vicinity, &c., of some connection 
with a fault-plane. 

In the valley of the Upper Kokatahi, just on the boundary of the subdivision, are several 
thermal springs, the waters of which are charged with, sulphuretted hydrogen, and deposit 
silica.* 

A larger and hotter spring than any of these was discovered by the topographical party 
on Cedar Flat, about three-quarters of a mile above the Toaroha Canyon. The spring, which 
is situated at the foot of a terrace on the left bank of Wren Creek, about 150 yards from the 
Toaroha River, has a temperature of from 150" to 160° Fahr. The visible flow of water is 
only a few gallons per minute, but a great deal percolates through the gravel, and quicklv 
fills any hole that may be made. Probably a large amount of hot water could be obtained 
by sinking a small shaft. The spring smells strongly of sulphuretted hydrogen, and deposits 
silica in long white threads, together with a little sulphur. 

An analysis of this water is as follows (results expressed in grains per gallon) ; — 
Silica .. .. .. .. .. .. .. 7-.3 

Calcium-sulphate . . . . . . . . . . . . 0-1 

Chlorides and sulphates of sodium and potassium . . . . 20-6 

Sulphuretted hydrogen .. .. .. .. ..1-9 

The sulphuretted hydrogen would no doubt have been considerably higher if the sample 
could have been analysed immediately after being taken. In composition this water is 
similar to that of the Taipo Hot Spring, except that it contains no magnesia. f 

Several thermal springs occur in the upper valley of the Mungo, a locality very difficult 
of access. On the left or southern bank of the river, a little below Brunswick Creek, there 

* Bull. No. 1 (New Series), N.Z.G.S., p. 39. 

t For analysis of the Taipo Spring, see Bull. No. 1 (New Series), N.Z.G.S., 1906, p. .39, 



63 

are two hot springs about 250 yards apart issuing close to the river from the gravels of a low 
terrace. Both smell strongly of sulphuretted hydrogen, and deposit white threads of silica. 
The upper spring has a temperature of not less than 150° Fahr., and at the time of the writer's 
visit the visible flow was 2 or 3 gallons per minute. Just above Brunswick Creek, on the 
south bank of the Mungo, is a third warm spring, but the flow is very small. 

A small mineral spring occurs on the east side of the Main South Road, a little beyond 
Lake lanthe. and not far from the Government hut. Its water smells of sulphuretted hydrogen, 
and deposits a little silica, but, unlike that of the other mineral springs of the area, is perfectly 
cold. 

There are several hot springs issuing along the banks of Hot Spring Creek, not far above 
its junction with the Wanganui. When visited, just at the close of a long spell of drv weather, 
these springs were very small, and their temperature did not exceed 100° Fahr. There was the 
usual smell of sulphuretted hydrogen, and small deposits of silica were observed. Personal 
communications made to the writer by several reliable persons who have visited the springs 
make it quite evident, however, that the flow is sometimes much larger, and the temperature 
higher. 

A curious circumstance may be mentioned here — namely, that some, if not all, of the 
hot springs in Westland are more active after heavy rain than during dry weather. This was 
noticed to be the case with the Toaroha Hot Spring, and the same phenomenon no doubt 
appears in these Wanganui springs. Attention has lately been drawn * to a connection between 
the level of surface water and hot-spring activity in the volcanic zone of the North Island 
of New Zealand, and we now have evidence of a similar connection in a region composed mainly 
of old sedimentary rocks. 

By far the largest mineral spring in the area under description is situated on the south 
l)ank of the Upper Wanganui, about 300 yards below the Smyth Stream junction. At the time 
of the writer's visit the visible flow of water was about 100 gallons per minute, and the tem- 
perature a very pleasant one for bathing purposes, or, say, somewhat over 100° Fahr. There 
is a moderately strong smell of sulphuretted hydrogen and but a small deposit of silica, so 
that the water probably contains little mineral matter. A much smaller spring of similar 
temperature occurs close to the water's edge about 100 yards higher up the river. 

Small thermal sprii'gs which smell of sulphuretted hydrogen have been occasionally 
observed at the water's edge on the east side of the Wanganui River, near the ferry. 

In quite a number of places a smell of sulphuretted hydrogen, which may be taken as 
evidence of the probable existence of a mineral spring, was observed without any spring being 
detected. These localities were: (I) a little below the lowest gorge of the Waitaha River; 
(2) in the upper valley of Hende Creek ; (3) near the junction of the Wanganui and Lambert 
rivers ; and (4) on the south bank of the Upper Wanganui, about a mile below the Smyth 
Stream junction. 

In all these places there is more or less evidence of faulting, shown either by the topo- 
graphy, or by shattered rock, irregular strike and dip, &c. 

Lakes. 
The only existing lake of any consequence in the Mikonui Subdivision is lanthe, a beauti- 
ful sheet of water which lies at the foot of Mount Bonar. It has an area of about 1,209 acres, 
with a length of two miles, and a maximum width of one and a half miles. The results of 
the numerous soimdings made by the Geological Survey party are indicated on the maps of 
the Waitaha and Mount Bonar survey districts. Its greatest depth was found to be 105| ft., 
but more than half of the lake is under 20 ft. in depth, and nmch towards the south end is less 
than 10 ft. deep. The surface of the lake is about 80 ft. above sea-level, so that its deepest 



• J. M. Maclaren: "The Source of the Waters of Geysers," Geol. Mag., Nov., 1906, p. 511. 



64 

part is a little below sea-level. The bottom consists everywhere of soft mud, which in the 
shallower parts supports numerous water-plants. 

Lake lanthe is a portion of the old Wanganui Lake, presently to be mentioned, which 
has not been filled up by the recent gravels of the Wanganui River, o-\ving to its being to the 
east of the course taken by the river on its way to the sea. 

Somewhat comparable with Lake lanthe, though occupying only 30 or 40 acres, is Lake 
Arthur, a pretty little sheet of water surrounded on three sides by morainic material. It 
will be found in the Toaroha Survey District, between Doughboy Hill and Momit Harrv. 

Among the low hills south-west of Koiterangi are four ponds occupying hollows which 
have been produced along fault-lines either by actual subsidence or by slight warping move- 
ments. Two of these, named Zala Pond and Teal Tarn, lie south-east of Pigeon Hill. The 
other two ponds are north-east of Doctor Hill. 

A small pond near the Kakapotahi River a short distance north of the foot-bridge, is 
a remnant of an old channel of that streagi. 

Lake Lyes, situated at an elevation of 2,640 ft. in the valley of Vincent Creek, is a small 
sheet of water which has probably been dammed back by a slip. 

There are numerous small tarns above the bush-line on the gentler mountain-slopes, 
ranging from pools a few feet in diameter to perhaps half an acre. It may be suggested that 
the hollows they occupy are usually due to wind erosion. 

Former Lakes of the Area. — There can be no doubt that the Mikonui Subdivision was 
once far more plentifully supplied with lakes than is now the case. The majority of the 
numerous rock-basiiis in the mountain-valleys now filled with river-gravels must have been 
lakes of greater or less size at some period in their history, but more particularly immediately 
after the retreat of the glaciers. 

Each of the three main areas of lowland plain described on page 46 was in all probability 
formerly a lake partly rock-bound, partly dammed by morainic material. The formation 
of these lakes must, in the first place, be referred to the faulting which has taken place along 
the western border of the Southern Alps, depressing much of the old land-surface below sea- 
level. The manner and extent of the faulting are debatable questions, which wiU be dis- 
cussed on another page. It may have taken place either immediately before or during the 
glacier-extension period. The view adopted here is that glaciers advanced from the Southern 
Alps over the present lowland area, and, more or less coalescing, gave rise to huge lateral and 
terminal moraines, enclosing large basins, which were ice -filled until the retreat of the glaciers 
and then became lakes. These, however, were soon fi.lled by the gravels of the rivers, that 
took the place of the glaciers as they rapidly retreated into the mountains. While in 
existence the piedmont glaciers protected the hollows from being filled, because they carried 
their debris forward or deposited it as lateral moraine. 

Lagoons. 

On the Westland coast there is a tendency for all the streams entering the sea to be dammed 
back by bars formed of material either brought down by the river or cast up by the waves and 
currents of the sea. In consequence, the stream tends to form a channel parallel to the shore, 
and separated from the sea only by a narrow strip of sand. The two largest rivers of the area, 
the Waitaha and the Wanganui, are so powerful, however, that they make their way almost 
straight to sea, though some attempt to form a lagoon is in both cases apparent. Streams 
of medium size are more successful in lagoon-formation, whilst small streams may either lose 
themselves in the sandy beach, or form httle lagoons of a temporary and shifting character.^ 

The most typical lagoon in the Mikonui Subdivision is Ounatai or DufEer Lagoon, a shallow 
strip of water into which DufEer Creek, Te Raho-Taiepa Stream, and several smaller water- 
courses emptv themselves. Its length of four miles is very great in comparison with its width, 
which even at high water nowhere exceeds 100 yards. The strip of low sandy ground between 
the lagoon and the sea is seldom more than 100 yards wide at high tide, and at some places 



65 

is 80 low and narrow that heavy seas wash over it into the lagoon. According to an old map 
Ounatai Lagoon formerly had an outlet at each end, but at present there is only one, situated 
about the middle of the lagoon, not far from the mouth of DufEer Creek, and almost exactly on 
the site of an old outlet which a few years ago was dammed by the beach-sands. That there 
is considerable soakage backward and forward through the sandy bar between the lagoon and 
the sea may be inferred not only from the nature of the barrier, but also from the numerous 
springs seen along the beach when the tide is out. 

At the mouth of the Mikoniu River a small lagoon— Donoghue Lagoon— extends for about 
half a mile to the north. It is separated from the sea by the usual sandy strip, and when 
seen by the writer had no outlet. 

The Shore-line. 

The shore-line of the Mikonui Subdivision stretches north-east and south-west from a 
point some two miles north of Ross to the mouth of the Wanganui River, a distanc^e of aboul" 
twenty-two miles. The most .striking features about the coast-line of this part of Westland 
are the lack of marked indentations, save the mouths of the various streams, and the uniformity 
of its direction. At the mouth of the Mikonui there is a rudimentary delta, and Bold Head, 
three miles to the south, also advances slightly beyond the general line. A few miles further 
south the morainic accumulations of the ancient Wanganui Glacier give rise to a very notice- 
able jutting-out of the coast-line. 

From Ross to Bold Head the strand is of the character usually accompanying a coastal 
plain. We see at low tide a wide, gently sloping beach composed of sand and fine gravel, 
backed by low sandhills. In calm weather a long, low .swell lazily rolls in, gradually spending 
itself on the beach. Wlien a westerly gale is blowing great white-crested billows come madlv 
sweeping shorewards, but the sandy beach checks their onset and curbs their fury. Occasion- 
ally the waves prevail so far as to sweep away for a time a portion of the beach, but the gap 
is soon filled up. and, thanks to the material .supplied by the rivers, the beach on the whole 
more than holds its own. 

At Bold Head the base of the blufE is seen to be protected by an accumulation of huge 
boulders, outside of which more or less sand is visible at low tide. The boulders, however, 
are not so efficient a safeguard to the land as the sandy beach. The victory of sea over land 
is evidenced by the clifF which forms the front of the bluff, and huge boulders far bevond low- 
water mark bear witness to the former extension of the blufE. 

South of Bold Head to just beyond the southern extremity of the Ounatai Lagoon the 
coast-line is simdar to that -north of the headland. Beyond this point the beach, .still com- 
posed of sand and gravel, has a background of difEs 40 ft. to 60 ft. high, which consist of 
morainic debris and coarse ttuvio-glacial gravels. 

Near the mouth of the Waikoikoi Stream the sea-clifE ends for a short space. South of 
the stream large cobbles soon appear on the beach about high-water mark, and as the Wanga- 
nui Blufi is approached, huge scattered boidders are seen on the strand. From this point 
the beach is of a most remarkable character. For several jniles it is largely composed of 
immense blocks of grauwacke and other rocks piled together indiscriminately, and derived 
from the morainic clifEs which front the sea. At or near high water the traveller finds pro- 
gress over this medley of rock very difficult, but when the tide is out there is more or less sandy 
beach outside and between the boulders. The amount of sand, however, varies greatly from 
time to time. Where, too. the purely morainic faces give way to lower cliffs composed of 
fluvio-glacial gravels, as is ui places the case, the boulders become smaller, and there is a good 
sandv beach exposed even at high tide. In .stormy weather, however, it is a difficult matter 
to make a passage round the cliffs, even at low tide. 

Nowadavs hardiv one person a year passes the Wanganui Bluff, and it is somewhat 
difficult to realise that in the early days of the goldfields the highway from Hokitika to 
South Westland was along the beach, and the Wanganui Bluff was passed by thousands 

5 — Mikonui. 



66 

of gold-seekers. At low tide horses were taken past the bhiff, though often with much 
difficulty. 

With the miners came the well-known author of the " Geology of Canterbury and West- 
land," at that time Canterbury Provincial Geologist. Graphically he has described for us 
both the stirring scenes which he witnessed and the geological phenomena which presented 
themselves to his keen eyes. Among these, Bold Head and Wanganui Bluff received special 
attention.* 

Fans. 

Many of the minor streams, where they emerge into the wide river-valleys or on the low- 
lands, have formed fans of considerable size. Owing to the open character of the material 
forming these fans, the streams often entirely disappear during fine weather, their water 
soaking away through the gravels. Among the larger and more conspicuous fans are those of 
Vine Creek (Koiterangi district), Anderson Creek (Waitaha Valley), and Cowhide Creek (a 
tributary of Evans Creek). 

One of the chief conditicms favouring the formation of a large fan is the existence in the 
stream-watershed of soft and broken rock, which, besides being easily eroded, is apt to break 
away in large slips. 

Talus. 

In the upper river-valleys, at heights approaching or above the bush-line, great shingle 
01 talus slopes are very noticeable. Their formation is due largely to the intense denudation 
of the high coimtry. This is favoured by the absence of bush, and greatly aided by frost. 
Talus-slopes are also common in the lower river-valleys and on the outer borders of the moun- 
tains. Both here and in the higher valleys talus-deposits merge into creek-fans. 

It should be noted that the lateral moraines of the ancient glaciers are often largely talus, 
which may have been dejiosited near the side of the glacier, and, after the retreat of the glaciers, 
upon true lateral moraine. Such talus can hardly be distinguished in structure from moraine, 
but the distinctly local character of the materials composing it indicates its origin. In some 
cases a glacial origin may be ascribed to a pure talus-deposit, on account of its similarity to 
lateral moraine. 

Slips. 

Everywhere the Mikonui mountains and hillsides show numerous slip-scars, some fresh, 
some many years old, and covered with young bush. The abundant rainfall of the area is 
one of the chief causes of slips, whilst another is the frequent occurrence of fault-crushed 
zones of rock. 

Two slip-areas deserve special mention. The first of these is on the east side of the Whit- 
combe River Valley, a short distance below Price Flat. Here for a distance of about a mile 
the whole side of the valley appears to be unstable. Where the surface is not actually bare, 
the short shrubby nature of the bush indicates that it has not been at rest long enough to 
enable large trees to make any growth. Owing to the unequal movements of the surface, 
the foot-track leading up the valley has already been dislocated in several places. During the 
stay of the Geological Survey party in the Whitcombe Valley such a movement took place 
after a heavy rain, breaking the track in two places. 

The other slip to be described is one of the largest in New Zealand, and is near the head 
of the Waitaha Plain. Here, about ten years ago, what is said to have been a spur of Mount 
Allen began to break away. Slipping of the broken schist rock went on for years, till at last 
a deep valley was formed where the crest of the spur had been, and the debris covered almost 
a square mile of country (see topographical map of Whitcombe Pass Survey District). The 
debris reached the Waitaha River, forcing its channel to the west, and raising its bed by 



♦ Von Haaat: " Geology of Canterbury and Westland," 1879, pp. 94-95, 393-395. 



PJ.ATE XYI. 







\ iKw i)v Mor.vT Ar.r.KX (.\nofT o.OOO kt.)- The Waitaha Slip appears on the right, and the 

WHOr.E POREfl HOUND IS OF DeHRIS I'ltO:^! THE SlIP. 







J.uuKiM. South up W.uiaha \'ai.i,lv to Smyth Kaxue. Debris frum Waitaha Slip on lett. 



aeol. JiiiU. Xo. fj.] 



[To face paye 66. 



67 

several feet for some miles down. The finer material gave rise to quicksands, which, how- 
ever, have now almost disappeared. Another effect of the slip was the almost total destruc- 
tion of the various grassy islands in the river, as well as, of course, of the agricultural land 
over which the debris spread. (See Plate XVI.) 

The criLshed. broken nature of the rock which slipped shows that this part of Mount 
Allen has been subject to fault -movement on a large scale. 

It may be added that slips assist greatly in the formation of creek-fans and talus-slope. 
The debris from the Waitaha slip forms a fairly gentle slope, which much resembles a true 
creek-fan. 



5* — Mikonui 



68 



CHAPTER V. 



FAULTING AND WARPING, WITH THEIR PHYSIOGRAPHIC AND GEOLOGICAL 

EFFECTS. 



Faults of the Area 

Introductory 

(].) Faults of the Main Range 

(2.) Faults of the Foothill Area 

(3.) The Great Thrust-faults 
VVarping and Tilt'ng 
Physiographic and Geological EflFects 

(1.) Physiographic and Geological Bound 
aries formed by Fault- planes 



Page Page. 

OS Physiographic and Geological Effects — 

68 continued 

68 (2.) Areas of Depression .. ..73 

^*' (3.) Valleys and River-courses . . 73 

_.-, (4.) Changes of Stream-grades .. 74 

73 (5.) Rock-basins . . . . . . 74 

General Conclusions . . . . . . 75 

73 



Faults of the Area. 

Introductory. — In a remarkable paper,* which forms a noteworthy addition to our geological 
literature, McKay, with a considerable measure of success, has sought to prove that the 
present outline and many of the modern physical features of New Zealand were determined 
by a series of great faults of comparatively recent date. He attributes the disappearance 
of the high land which once existed west of Hokitika to a combination of four or five faults 
which intersect in that region, f and indicates, without actually describing it, the occurrence 
of a great fault along the western base of the Southern Alps.| 

It has already been stated that a great reversed fault or thrust-plane actually forms the 
western boundary of the main mountain-range, separating it from the lowlands and the 
rocks of the Greenland Series.§ This, then, is the master fault of the Mikonui Subdivision ; 
but there are many other faults, some of great importance, within the area. These, together 
with the main dislocation, will be briefly described under the headings of — (1) Faults of the 
main range ; (2) faults of the foothill area ; (3) the great thrust-faults. 

(1.) Faults of the Main Range. — In the course of field-work it became evident that the 
rocks of the main range are traversed by almost innumerable faults. These can be recognised 
by zones of crushed rock, by sudden changes in dip or strike of rock, and occasionally by 
indubitable fault-scarps, or by visible dislocations of the strata ; but it is often very diffi- 
cult to determine the significance, or even the direction of the faulting. Recognition of 
fault-planes has in some instances been aided by the existence of hot springs, which are thought 
in all cases to be more or less connected with deep-seated fault-movements. 

Many of the faults, being merely local movements which have affected small areas on the 
mountain-slopes, are of no structural importance, and many others, though perhaps of con- 
siderable length, and extending to notable depths, represent comparatively slight dislocations 
parallel to the strike produced during the folding of the beds and the elevation of the moun- 
tains. 

Of considerable significance, ho-wever, is the faulting which is manifest wherever the talc- 
schists appear. The talc-schists are confined to the western part of the main chain, and 
were formed from mica-schists or similar rocks by the influence of the magnesian solutions 



* " On the Geology of Marlborough and South-east Nelson," Part II, G.S. Rep. dtirins 1890-91, 
vol. xxi, 1891, pp. 1-28. 
t Loc. cit., pp. 26-28. 
j Loc. cit., p. 3. 
§ See Bull. No. 1 (New Series), N.Z.G.S., 1906, p. 40. for reference to a possible great structural break. 



69 

which accompanied or succeeded the intrusion of the ultra- basic rocks which have given rise to 
the Pounaiuu Formation. 

It is thought that the luagnesian solutions followed dislocations which are intimately con- 
nected with the overfolding of the western part of the schistose rocks, and that the ultra- 
basic rocks themselves rose along the planes of such dislocations during the mountain-building 
process. 

A strike-fault of considerable importance is believed to be indicated by a number of 
small flats which occur along a line drawn south-west from near the head of Crawford Stream 
(in Browning's Pass Survey District) to a point in the Toaroha Valley about a mile from the 
source of the Toaroha. As defined, this line begins and ends with small flats, whilst along 
its course are the flat at the junction of the Crawford and the Kokatahi, the flat at the head 
of the Kokatahi, and Zit Saddle. If continued for some miles to the south-west, it crosses 
the Whitconibe Valley at Price Flat. Faulting along this hne is confirmed by the occurrence 
of disturbed and crushed rock at various points. 

In the vicinity of this supposed fault-line there is a fairly rapid change in the metamor- 
phism of the rocks, phyllites and schists on the west giving way to slightly schistose grau- 
wackes and argillites on the east, a circumstance which may not be without significance. 

South of Pinnacle Creek a fault traverses the valley of the Kokatahi for some distance, 
as is shown by discrepancies of dip and the occurrence of great quantities of crushed rock. 
Above the junction with the Crawford a north-and-south fault, indicated by the hot springs 
and the absence of outcrops of solid rock for some distance, seems to follow the valley. 

There are several faults in the valley of the Toaroha, but to most of these no particular 
direction can be assigned, though their presence is proved by variations in dip, by crushed 
rock. &c. One, however, can be plainly seen as a sunken line on the ridge south of Zit Creek, 
and a contiimation to the south is indicated by scarps, or depressions in the ridges. The 
fault is pvidentlv of recent date, but the visible movement is not great. It has a strike 
of about 169", and a westerly dip. 

About two miles above the junction of the Hokitika with the Whitconibe a fault with a 
strike of about 290^ is seen. Its existence is shown by marked discrepancies in character of 
the rocks on either side of the river, the schists on the north side being shattered and dipping 
at low angles to the south-east, whilst those on the south side are solid and have an almost 
vertical dip. Two outcrops of talc-schist on opposite sides of the river, which weie thought 
to belong to the same band, are decidedly out of line, and indicate a westward hea\ e on the 
north side of the fault. If extended to the west, the fault-line crosses Collier Creek, a tri- 
butary of the Lower Hokitika, near its mouth. Here, again, there is evidence of faulting 
presented by low dips and crushed rock, whilst a band of talc-schist again is out of line with a 
similar band which outcrops half a mile to the south near the Hokitika River. To the south- 
east the extension of the fault is shown for a short distance by crushed rock. 

A little al)ove Serpentine Creek the valley of the Hokitika is followed for a mile or more 
by a fault which seems to run from west of north to east of south. Its existence is inferred 
from the extremely shattered nature of the rock-outcrops. Considerable strike-faulting has 
taken place along the lower valley of Serpentine Creek, as is shown by a zone of crushed rock 
and the slickensided surfaces of the serpentine-schist which here outcrops. 

Above Frisco Canyon the valley of the Hokitika and its continuation, that of the Mungo, 
are followed by a fault which is indicated by crushed rock, by the unusually straight valley, 
and by the hot springs near Brunswick Creek. The fault runs slightly north of east. To 
the west it seenjs to pass over Meta Saddle, where there is abundant evidence of faultmg 
exhibited not only by the topography, but also by much crushed rock outcroppnig m the 
upper part of Saddle Creek. A contiimation of the fault as far as the Whitcombe River is 
.shown by crushed rock in Tom Creek. 

In every part of Meta and Conwav lidges numerous minor faults of very recent origin can 
be seen. Generally they are indicated by small cliffs or scarps and by clefts of great depth. 



70 

From tlip junction of the Wliitconil)e River with the Hokitika to Whitcombe Pass there 
are numerous indications of faulting afi'orded by the disturbed and crushed nature of the 
strata. These signs are seen more particularly on the east side of the river, above the Cropp 
junction. It is probable that a fault striking from west of south to east of north extends from 
Whitcombe Pass to the neighbourhood of Frew Creek. Here it meets the Mungo River fault, 
but a continuation to the north for another mile at least is apparently proved by a zone of 
crushed talc-schists in Harry Creek. The long, straight valley on the Canterbury side of 
Whitcombe Pass may indicate a southward continuation of the Whitcombe Valley fault. A 
slight earthquake which was noted by several members of the Geological Survey party on 
the 5th April, 1907, shows that fault-movement in the Whitcombe Valley may still be in 
progress. 

The much-crushed zone of rock which has given rise to the Waitaha Slip appears to be 
due to a series of faults more or less parallel to the Gregory Valley overthrust (see page 72). 

The western slope of the Lower Waitaha Valley is, like the east, probably a fault-scarp. 
The Waitaha Valley is therefore an example of a graben. 

In the Wanganui Valley, evidence of faulting is furnished in several localities by thermal 
springs, by numerous shattered outcrops of rock, and by irregular strikes and dips. 

Many other probable fault zones might be enumerated, but the attendant phenomena are 
in all cases much the same. Owing to the great similarity in the beds afiected, it is almost 
always impossible to judge even roughly the amount and direction of throw or thrust. The 
rugged nature of the country, while favourable for detecting signs of faulting, tends to prevent 
any definite data from being obtained. The dense bush or scrub at all levels below 3,500 ft. 
is in every way an obstacle to accurate determination of the faults, and in many cases a more or 
less incorrect impression of the direction may have been obtained. 

While the faults observed strike to almost every point of the compass, there is a 
tendency for them to favour certain lines. The most common directions are about 10° 
to 20° on either side of the meridional line, and 10° to 20° on either side of the east-and- 
west line. 

(2.) Faults of the Foothill. Area. — Koiterangi Hill is traversed by a number of small faults 
which dislocate the coal-measures : but, apart from these, it shows, as mentioned on page 41, 
evidence of being a block mountain. (See also Plate XXII.) 

The sudden di-op on the east side of Doctor Hill cannot easily be explained without 
assuming a north-and-south fault. If the patch of coal-measures reported to exist in this 
neighbourhood had been located, confirmation of faulting would have been furnished. 

On its west side the valley of Falls Creek is followed by a considerable fault, which strikes 
slightly west of north on a Ijearing of about 354". Towards the north end of the valley small 
ponds and swamps to the east of the line indicate depression, perhaps caused by a parallel 
dislocation. Near Pigeon Hill a straight, narrow valley on the line of fault has all the ap- 
pearance of a fault-rift. The fault continues over a low saddle into the valley of Granite Creek, 
where its presence is indicated by shattered rock. The eastern side of Pigeon Hill shows 
a scarp due to this fault (see Plate XXII). 

The last-described fault is crossed near Pigeon Hill by a second fault, indicated by a 
narrow, mnnistakable rift valley, in which is a depression containing a swamp and a pond 
(Zala), and by an outcrop of slickensided crushed rock on the north side. The fault has a 
strike of about 104°. and, as shown by the outcrop just mentioned, appears to dip at a rather 
low angle to the south. Probably the main fault is on the south side of the valley, and dips 
to the north, as indicated by a scarp on the north side of Pigeon Hill. 

In the neighbourhood of Ross there has been faulting on an enormous scale. By it the 
Upper Miocene beds have been tossed in all directions, whilst great bands of finely crushed 
grauwacke in the valleys of Donnelly and ~Bayley creeks testify to its action on the older 
rocks. The occurrence of river-gravels on the higher slopes of Mount Greenland seems to 
indicate a recent dislocation, with downthrow to the north-west, of nearlv 3,000 ft., for at the 



71 

foot of the inoiintaiii similar gravels are seen almost at sea-level.* Though this inference 
must be accepted with some reserve, the relative positions of the various patches of Upper 
Miocene strata prove a fault with throw of at least 1,000 ft. in this locality. So far as can 
1)6 judged from the topography and the bands of crushed rock, the main fault has a strike 
of about 240' to 250 . A small reversed fault, which had a downthrow of about 8 ft. to the 
north-west and a strike of 246°, was actually observed in Bayley Creek in a claim where the 
rock had been bared by sluicing operations. Here the finely crushed nature of the faulted 
rock indicates that the small dislocation is but part of a much greater one. 

If the hypothesis of former high land to the west of the present coast-line be admitted, it 
almost necessarily follows that the foothill district is limited on its western margin by faults. 
This, we have seen, is shown to be the case at Ross by actual field evidence. Between Ross and 
Koiterangi the boundary of the foothills runs a little north of east, from Ross to the Mikonui 
River the direction is north-east and south-west, whilst south of the Mikonui to the Waitaha 
Valley the boundary runs from east of north to west of south. These, then, are possible fault- 
lines. Of the first, crushed rock in Gow Creek affords some proof. Near Ross the tokens 
of faulting need not be further detailed. South of the Mikonui evidence of faulting is 
furnished by the tilting of the Late Tertiary beds at McLeod Terrace and of comparatively 
recent gravels near Ferguson's. Great faces of crushed rock in the valley of Shearer Creek 
indicate a north-aud-south fault nearly parallel to one of the outer bounding dislocations. 
Finally, the foothills are bounded on the west by the fault-scarp which forms the east side 
of the Waitaha Valley. 

(3.) The Great Thrtud-faiUtn. — In the section referring to the formation of the Southern 
Alps various reasons were given or implied for inferring the existence of a great overthrust 
fault along the western margin. These may now be restated in an amplified form. Suess has 
shown, in his monumental work " The Face of the Earth," that folded mountain-chains have 
generally been produced by thru.st up an inclined plane. Examples of this were proved by 
McKay many years ago to be afforded by the Inland and Seaward Kaikoura Ranges, in 
Marlborough. He has shown that the Kaikouras are of very recent elevation, and that during 
their elevation the Pahvozoic and Secondary rocks of which they are formed were thrust by 
forces acting from the north-west over Tertiary deposits in the Clarence Valley and on the 
eastern side of the Seaward Kaikouias.f Reasoning by analogy, we might expect to find 
the Southern Alps of similar structure. The steep descent on the western slope, together 
with the fact that the oldest rocks are here exposed, would lead us to look for overthrust on the 
VVestland rather than on the Canterbury side of the range. 

A second line of argument rests on the strong probability of intense overfoldiiig in the 
western six miles of the schists and gneisses, which have an almost constant easterly dip. 
The pressure necessarv to produce such overfolding, if it exists, must almost necessarily have 
pushed the whole alpine chain to the west, with the probable production of one or more 
reversed faults. 

Coming to the more direct field evidence, we find that the rocks of the western foothills 
possess a radicallv different folding in a direction almost at right angles to that of the main 
range, that the folding is less intense, and the degree of metamorphism far less pronounced 
than that of the strata to the east. The discrepancy of strike in itself indicates a great fault ; 
and further confirmation is furnished by the absence of any visible contact, and by the marked 
depressions along the line where contact might be expected. On the western side of Mount 
Bonar a fault zone is shown by the disturbed and crushed nature of the gneissic schists. Again, 
the granite intrusions along and near the western margin of the Alps are further evidence of 
deep-seated faulting. The granitic bosses are, as Suess puts it, cicatrices along a healed wound 

* See also McKay, " Geological Explorations of the Northern Part of Weatland," Mines Report, 1893, 
C.-3, p. 176. 

t " On the Geology of Marlborough and the Amuri District of NeLson," G.S. Bep. during 1888-89, vol. xx, 
190, pp. 97, 173, &c. See also P. Marshall, ' Geography of New Zealand," 1905, pp. 103, 104. 



n 

in tlie earth's crust. Lastly, near the head of Smyth Creek, Miocene rocks appear to pass 
under neighbouring gneiss, thus giving evidence of relatively recent overthrust. 

On theoretical grounds one might naturally expect to find that there was a series of over- 
thrusts rather than a single thrust-plane. Notwithstanding the plutonic intrusions, which 
have destroyed any evidence of thrusting that may once have existed immediately to the 
east of the main thrust-plane, proof of a second plane of overthrust is afforded by the ancient 
Gregory Valley. This is spoken- of by McKay as " a valley of erosion,"* which it no doubt is. 
It is certain, however, that it also represents a line of weakness which was easily worn down 
by denuding agencies. Its position parallel to the main overthrust, but on the east side of the 
granitic bosses, is most significant. Indirect evidence of a fault-plane parallel to the valley is 
afiorded by its straightness, combined with its very peculiar direction athwart the present 
drainage-lines. More direct evidence is furnished by the variations in strike, and to a less 
extent in dip| of the rocks outcropping along the course of the valley. The final line of e\d- 
dence is one of a more direct and convincing nature. North of Mount Bonar the rock-outcrops 
in the Gregory Valley do not show any decided sign of overthrust movement, because the 
probable overthrust bands rest against a granite or gneiss buttress ; but south of Mount Bonar 
the Gregory Valley runs into the lowlands, and its eastern side forms the western boundary of 
the mountains. Here there is not only an evident fault-scarp, but in Cowhide Creek and on the 
south side of the Wanganui zones of crushed rock appear. In Harold Creek, south of Hende's, 
discrepancies of dip and strike in the dark schists which here outcrop are manifest. Faulting 
is therefore certain. It may further be mentioned that on the north side of the Wanganui small 
hot springs occasionally make their appearance. A remarkable circumstance still has to be 
mentioned — that both at Cowhide Creek and at Hende's (see Plate XVII) the crushed rock has 
been pushed over recent gravels. At Cowhide Creek it might well be supposed that this is due 
to superficial thrust — that is, a mere slipping of the crushed rock over the modern fan gravels 
of the creek ; but at Hende's the topography is not favourable to such a view. The overlap, 
however, is of a superficial character, and it is just j^ossible that during the glacial-extension 
period ice may have given the necessary thrust. One ought for the reasons given, not to place 
much reliance on the curious phenomena presented at Cowhide Creek and at Hende's ; still, the 
coincidence of thrust or slip of the Palaeozoic rocks over modern alluvia in two spots not far 
apart on the line of fault furnishes food for thought. If overthrust is the explanation, it 
confirms the view that the Alps were undergoing elevation within the last few thousand years 
— an occurrence which is not unlikely, and one to which a parallel exists in the Inland 
Kaikoura Range, which is still being affected by earth-movements.J 

Warping and Tilting. 

.Since there is reason for thinking that the forces which have given rise to the present 
alpine chain, have produced overthrust faults it is natural to expect also the occurrence of a 
certain amount of warping. Proof of warping without faulting along lines more or less parallel 
to the main divide is thought to be furnished by certain marked irregularities of grade in 
many of the rivers and streams, but more especially by the existence of rock-basins. Some of 
these features are due to ice-action, but in others the topography is completely opposed to 
this view. The distinct rise of the main divide from north to south, amounting in the Mikonui 
Subdivision to nearly 2,000 ft., might also be included under the head of warping. 

Tilting produced by fault-movements is evident in the whole area occupied by the foot- 
hills, and is especially noticeable where Tertiary beds outcrop. 

* " Geo'ogical Explorations of he \oithern Part of VV'estland," Minew Rep or . 1893, C— 3, pp. 136, 143. 

t The terms " strike " and " dip " must here be understood as referring to schistosity as well as to bedding- 
planes. 

X For instance, during the earthquakes of 1848, 1855, and 1888. Vide McKay's repoi-ts " On the Geology 
of Marlborough and the Amuri District of Nelson," pp. 86, 96, 98, &c., and '• On the Geology of Marl- 
borough and South-east Nelson," Part II, pp. 10-11. 



PLATE XVII. 




View thum nkai! Moim .\Iii;i.i.eh, snowixf; Amisi Domi-; (on i.ekt), Iikd I^ion, and Mount Evans 
(in cexthaf- backciiound). Vai.i.ky of Wanganui below. 

I'hiiln liij /.mill-- (iiiil Siirriij Dc/mrfiiirnf. //ohitll.a.] 




View of Cuff Face neak HnNDE'f? Fkrry. showing SiiATTEUED Dahk Schist pushed over 

IvIVEK-GRAVELS. 



Ocol. Hull. Xo. 6.] 



[To face p(i(j( 



73 

No attempt will be made at present to define exactly the amount or direction of the warps 
that have affected the subdivision, but some of the following paragraphs will give an idea of 
the manner in which the area has been afiected by recent flexures or irregular uplift. 

Physiographic and Geological Effects. 

(1.) Physwyrai>hic and Geological Boundaries formed by Fault- planes. —The account given 
of the various faults of the area under description shows that the western boundary alike 
of the alpine chain and of the highly metamorphic rocks is formed by the great reversed fault 
described on page 71. The foothill area and the Greenland Series are in like manner ooter- 
minously bounded by entirely surrounding faults. 

The various areas of coal-measure rocks are also more or less fault- bounded, so that it 
becomes evident that almost all the main geological and physiographic boundaries of the 
area are faults. 

(2.) Areas of Depression. — In the first place, the whole of the lowland country is an area 
of depression, produced by the great faults which define the western boundaries of the alpine 
area and the foothills. More particularly the Kokatahi-Koiterangi Plain and the Waitaha 
Valley are hollows in this area which were formed to some extent by great faults transverse 
to the dominant north-east to south-west dislocations, and were left unfilled or partly so by 
the glaciers which have done so much to build up the lowlands. After the glacier retreat they 
were lakes for a time, until the rivers completed the filling-up process. Lake lanthe and the 
Wangaiuii Plain together form another somewhat similar area defined on only one side, the 
south-east, by a fault. Here the infilling is not complete. 

A second main area of depression lies along the eastern margin of the foothills. It is due 
to the outer or western portion having been elevated to a greater extent than the inner, and 
probably also to a certain amount of collapse along the fine of the great thrust-plane. Its 
effect is shown in a broadening of the valleys of Lower Doctor Creek (Sunshine Flat), Upper 
Doctor Creek (near Humbug Creek), Upper Mikonui (Gribben Flat), and Kakapotahi (Happy 
Valley). 

(3.) Valleys and Rirer-cuurscs. — It cannot l)e said that any river- valley in the Mikonui area 
except the Lower Waitaha has been produced by faulting, and none so far as known is due 
to warping, but the former agent seems to have had much infiuence in determining original 
direction. This is notably the case with the Whitcorabe and Upper Wanganui valleys. It 
may be noted that the main rivers of the alpine area seldom run at right angles to the strike — 
that is, along the lines of greatest gradient — but have a tendency to approximate either to 
an east-and-west or to a north-and-south line. These are also favourable fault-directions 
(see page 70), and there is apparently in most cases a casual connection though perhaps not 
always a direct one, between faulting and the general directions of the liver- valleys.* As 
regards the minor streams, it need only be said that quite a number follow fault-lines for 
portions or the whole of their courses. 

The effect of faults, and more especially of crush zones, such as those so common in the 
Southern Alps, in bringing about minor changes of direction, bends, &c., in stream-courses is 
so obvious that it need not be enlarged upon. 

A broadening of the valleys where they are crossed at any angle by a crush zone is a feature 
of common occurrence. 

.Attention mav also be drawn to the remarkable bends or complete changes of direction 
made bv the Kokatahi, Waitaha, Wanganui, and to a less extent by other streams along a 
north-east and south-west line drawn a few miles east of the western boundary of the Alps. 



• This statement ought to be qualified by saying that the directions of some of the mr in river- valleys 
may pos-sibly have been determined in pre-iMiocene times. If such be the case, faulting canuC, well be invoked 
as determining the stream-direction, and the rivers occupying these valleys are possibly obseiiuent streams. 
la this connection, vide Hochstetter, ■ New Zealand," English edition, 1867, pp. 483-6; or Von Haast, ' The 
Geolog\- of Canterbury and Westland," 1879, pp. 175-76. 



74 

This is also approximately (though not exactly) the line of the serpentine outcrops, and there- 
fore these bends, it has been thought, are causally connected with the Pounamu Formation. 
In the Waitaha and Wanganui valleys, however, serpentine is represented onlv bv one small 
outcrop in the former valley. It is far more probable that these bends are connected in some 
way with the fault-planes along which the Pounamu rocks were intruded. Outside the sub- 
di\'ision the Arahura River makes a remarkable snake-like bend where crossed bv the 
horizon of the Pounamu Formation. 

(4.) Changes of Stream-grades. — The remarkable changes in grade seen in most of the 
main,^ river- valleys were mentioned in the last chapter. It was then suggested that a varia- 
tion in grade might be produced by the action of glaciers in flattening certain parts of river- 
valleys, whilst the portions below were protected by morainic material : but this explanation 
cannot be applied to several notable instances, for which the most probable cause that can 
be assigned is undoubtedly warping or tilting. 

(5.) Rock-basins. — Attention has often been called to the numerous little flats which 
occupy rock-basins in the alpine valleys.* In the Mikonui Subdivision rock-basins of various 
sizes are common in all the river-valleys of the alpine area. In addition, there are several 
in the foothill country. The chief of these are the upper valley of Falls Creek, the upper valley 
of Doctor Creek (this is probably connected with Falls Creek Valley), the L'pper Mikonui 
Valley (Gribben Plat), and the Kakapotahi Valley (Happy Valley). (See Plate XXI.) 

In order to account for the formation of these rock- basins various hypotheses were con- 
sidered. The most obvious cause was the agency of glaciers, which many geologists strongly 
advocate as capable of forming deep rock-basins. Whatever glaciers may have done elsewhere, 
it was soon manifest that with one or two exceptions they have not produced any of the larger 
rock-basins in the area. A prime i-eason for rejecting glacial action is that the river-valleys, 
except at their heads, are not the U-shaped valleys formed by glaciers, but are almost typical 
valleys of stream erosion, the Browning Valley possibly excepted. 

The \'iew that some of the larger rock-basins were down-faulted areas, or graben, had 
to be summarily cast aside except as regards the Falls Creek Valley, and for this also it was 
finally rejected as the sole explanation. 

Further consideration has made it clear that almost all the rock-basins of any conse- 
quence are due to warping and tilting caused by uneven uphft and cross-faulting, which has 
raised or depressed certain points of the river-valleys relatively to others. This appUes more 
particularly to the foothill area. Taking Gribben Flat as an example, it is evident that this 
rock-basin was produced by the raising of the lower seaward part of the Mikonui Valley to a 
greater extent than the upper portion. That differential elevation has taken place in the 
required manner is shown by the occurrence of Upper Miocene beds at 700 ft. or 800 ft. above 
sea-level in Slate and Smyth creeks (see Chapter IX), whilst beds of similar age are seen near 
sea-level at Ross, and at 1,100 ft. or more on the slopes of Mount Greenland. The attitude 
of the rocks forming the Koiterangi Series lends further support to this conclusion. 

Happv Vallev and Falls Creek basins have been produced by the same processes as 
Gribben Flat, though in the latter case faulting has also been in e\-idence. The rock-basin of 
Upper Doctor Creek (near Humbug Creek) is practically an extension of the Falls Creek basin. 

As regards the flats within the alpine valleys, the conclusion that they are due, with 
a few exceptions, to warping (combined in .some cases with notable strike-faulting) has been 
reached largelv by excluding glacier-action and direct faulting. It could not be perceived 
with certaintv in any case that they were caused solely by faulting, and therefore they have 
been attributed to wai-ping. They are of the shapes that might be expected from such an 
agency, whilst the existence of gorges above and below many of these river-flats, even apart 
from other topographical features, appears to exclude glacier excavation, which is practically 
the only other tenable hypothesis. 



* A. P. Harper, " Pioneer Work in the Southern Alps of New Zealand," 1896, pp. 186-7. 



75 

General Conclusions. 
From the statements in the preceding pages, the conclusions may be drawn that the rocks 
of the Mikonui Subdivision have been affected by numerous faults, often of great throw. 
In the foothill area the chief geological boundaries are defined by faults, from which also con- 
siderable tilting with formation of several large rock-basins has resulted. In the alpine chain, 
besides faulting, wai"ping seems to be in evidence : but there is considerable difficulty here 
in differentiating between the effects of mere warping and of faulting, owing to the complexity 
of the folding and the absence of well-defined horizons in the strata. Warping and tilting are 
proved not only by direct evidence, but also by the numerous rock-basins and less certainly by 
the varying river-grades. (Jlacier-action as a possible cause for the larger rock-basiiis has been 
fully cou.sidered, and rejected in most cases. Finally, there is evidence that many of the 
faults and warps are of recent origin, and some may possibly still be proceeding. 



76 



Page 
76 

"7 


General Petrology — continued. 
(2.) Mica- schists — coniiniud. 




Page 


77 


(h.) Quartz-schists 




.. 84 


78 
78 
79 


(c.) PhyUites . . . . . . 84 

(d.) Doubly Metamorphosed Rocks 84 
(3.) Less Altered Grauwackes and Ar- 


79 
79 


gUlites 
(a.) Subschistose rocks 




.. 85 
.. 85 


80 


(6.) Non-schistose rocks 




.. 85 


80 
81 


Special Petrology 

(1.) Gneissic and Dark Schists 




.. 86 
.. 86 


82 


(2.) Mica-schists 




.. 94 


83 


(3.) Grauwackes 




.. 94 


83 


Analyses 




.. 95 



CHAPTER VI. 



THE ARAHURA SERIES. 



Age and Correlation . . 

Distribution 

Subdivisions 

Structure 

Period of Metaniorphism 

Causes of iletamorphism 

Thickness of the Series 

FossUs 

General Petrology 

(1.) Lower Gneisses and Schists 

{a.) Gneissic Schists . . 

(b.) Dark Schists 
(2.) Mica-schists 

(a.) Quartz-mica-schists 

Age and Correlation. 

It has already been stated that the vast assemblage of beds comprised under the name of the 
Arahura Series was deposited in Palaeozoic times, and apparently during one great period of 
sedimentation, along the slowly sinking shore of a continental land. The thickness of the 
series is so great that evidently it ought to be subdivided if possible. Previous observers have 
not only done this, using degree of metamorphism and other lithological characters as a basis, 
but have assigned definite ages to the subdivisions. In \'iew of the advanced metamorphism 
of the lower beds, and the absence of all fossils except a possible Dentalium and an annelid 
from the upper less metamorphosed beds, the latter proceeding must be considered decidedl}' 
premature, possible though it may be that further study will justify part of what has been 
done in this respect by former investigators. 

Cox, in 1877, separated some of the gneissose rocks (including certain banded granites) 
from the overlying metamorphic rocks or mica-schists which, he noted, in their lowest horizon 
contained gneissic bands.* The less altered grauwackes and argillites were placed in the Maitai 
Series, and considered to be of the same age as the auriferous rocks at Reef ton. The Maitai 
Series is generally believed to be of Carboniferous age. but doubt has lately been thrown on 
this view by Professor Park, who considers the Maitai Series to be of probable .Jurassic age.t 
Von Haast a few years later considered the highly metamorphic mica-schists and gneissic 
schists (including granite) to be of Azoic age ; while he placed the upper less metamorphic 
beds in his Mount Torlesse, Waihao, and Westland formations, which he regarded as belonging 
to the Upper, Middle, and Lower Palteozoic respectively. J 

In the detailed reports of McKay, published in 1893 and 1894, the Arahura Series is sub- 
divaded according to lithological characters. The highly metamorphic rocks are considered 
bv this writer to be pre-Devonian, and apparently he would assign an Arch;ean age even to the 
middle schists,§ whilst the slightly metamorphic rocks are classed as Devonian, and the upper 
grauwackes and argillites are placed in the Maitai Series. McKay confirms Cox's correlation 

♦•'Report on Westland District." G.S. Rep., during 1874 76, vol. ix, 1877, pp. 66. 71 73. 
t •• On the Jurassic Age of the Maitai Series," Trans., vol. xxxvi., 1903, p. 431. 
i " Geology of Canterbury and Westland," 1879. p. 251, &c. See also geological map. 
§ Sollas and McKay: " Rocks of Cape ColvUle Peninsula" (and other parts of Xew Zealand), vol. ii, 
1906, p. 198. 



77 

of the latter beds with the auriferous rocks at Reefton. as well as with typical Maitai beds 
occurring near Nelson. In the present bulletin the Maitai or Carboniferous age is tentatively 
accepted for the higher beds. The submetamorphic and metamorphic rocks are for the present 
classed as the lower beds of the same fornaation, but may possibly be Devonian and Silurian. 
The clearly sedimentary character of certain of the oldest layers, the absence of any general 
contortion, the apparent conformity of the lower beds with the upper, all strongly oppose 
the supposition that we have here any portion of the Archjean crust. 

To many geologists this grouping together of the whole of the rocks composing the alpine 
chain will appear a retrograde step ; but though the writer was strongly impelled to separate 
at least the lower gneissic schists, the absence of palaeontological data or other definite criteria 
has led him to follow the course adopted in the Hokitika Bulletin. 

Distribution. 

The Arahura Series in the Mikonui Subdivision extends over the whole area occupied 
by the alpine chain and its branches, and includes also the dark schists and gneisses of Mounts 
Harry and Misery, Fraser Peak, Bald Hill. Mikonui Sugarloaf, the eastern part of Purcell 
Ridge, and Mount Bonar. The western boundary is therefore defined by a line running south- 
west from the western extremity of Browning Range, following the eastern edge of the low- 
lands to Mount Mi.sery, then striking up the valley of Doctor Creek to Humbug Creek, and 
continuing past the north-west side of Bald Hill Range to the Waitaha Valley. South-west of 
the latter valley the rocks of the Arahura Series are found well to the seaward of the general 
line. From here to the Wanganui River morainic ridges and lowland flats form the western 
boundary. 

East of the boundary-line are several granite bosses and the various outcrops of the 
Pounamu Formation, but otherwise the whole area, superficial gravels excepted, to and beyond 
the main di\ade consists of the rocks of the series. 

SUBDIVI.SIONS. 

The .A.rahura Series, as developed in the Mikonui area, may perhaps best be given a 
threefold subdivision, based purely on physical characters. In spite of a careful and detailed 
.search, neither in the Hokitika nor in the Mikonui area has any distinct evidence of decided 
unconformity within the .series been found, such as a conglomerate band containing pebbles 
of the older beds. Though there are many minor irregularities, no general discordance of 
strike and dip exists anywhere, but the intensity of the north-east and south-west folding 
which accompanied the elevation of the Alps, and which, as stated on the next page, has, 
except on and near the main divide, quite ejffaced the earlier north-west and south-east 
folding, forbids the expectation that if such a discordance ever existed it could now be 
detected with any degree of certainty. 

There are, however, some slight indications of unconformity along a line which may be 
.said to sepaiate the more metamorphic from the less metamorphic part of the series,* but the 
discrepancies ot strike and dip can be referred with more probability to faulting or irregular 
folding, complicated by remains of the earlier plication. On the main divide near Mungo 
Saddle and Mathias Pass the irregularities of strike and dip also seem to be due to unevenness 
of folding, combined perhaps with faulting. The same explanation applies to the many minor 
irregularities met with elsewhere. 

The almost complete disappearance of the metamorphic characters as one proceeds from 
the lower to the higher beds has been taken by some writers as evidence of widely different age. 
But the change is a gradual and uniform one, nowhere sudden or decided ; and when one 
takes into consideration the great thickness of the beds concerned, and the general field evi- 



See abo Bulletin No. 1 (New Series), N.Z.G.S., 1906, p. 42. 



78 



dence, it seems certain that the variations in metamorphism are due not to variation in 
age, but to differences of heat and pressure, dependent upon varying depth below the earth's 
surface : or to other easily recognised causes, such as igneous intrusions, thermal solu- 
tions, &c. Tliis statement must be partly (jualified with respect to the dark and gneissoid 
schists, which arc largely of igneous origin, and differ in other ways from the overlying 
mica-schists. 

The following tabulation shows the subdivisions of the Arahura .Series adopted in this 
bulletin, together with those employed by McKay : — 



This Bulletin. 



/,> f(a) Gneissic schists 
^ ( (6) Dark curly schists 
(2) Mica-schists 

,„. f(o) Subschistose rock.s 
^ ({b) Non- schistose rocks 



McKay. 



Age according to McKay. 



Gneissoid schists .. .. .. (?) Archaean, 

Lower mica-schists . . . . . . ,, 

Middle mica-schists . . . . . . ,, 

Upper mica-schists . . . . . . Pre- Devonian. 

Slightly altered submetamorphic rocks.. Devonian. 

Maitai Series . . . . Carboniferous. 



Structure, 

The general structure of the Arahura Series is that of the mountain-chain of which it 
forms practically the whole. This was described on page 43, The strike, though generally 
near north-east and south-west, may vary from north and south to east and west. In one 
or two localities on or near the main divide it appears to be from west of north to east of south. 
It is somewhat significant that the lower layers towards the western boundary generally have a 
strike of about 240°, or occasionally more ; whilst towards the main divide the strike tends 
to approach a north and south line, and may even, as noted, turn to west of north. This 
change of strike is probably due to the influence of the older north-west to south-east folding. 
In the middle and lower layers of the western slopes it was completely obliterated ; but in 
the upper layers, towards the east and further from the main folding axis, the earlier folding 
was able to assert itself to some extent. 

The dip of the folds, except where influenced by local causes, such as faulting, or, as is often 
seen, creep down a hillside, is everywhere high : always over 60°, and generally over 80°. Dips 
of 90° are common, and in places the folds are evidently slightly overturned. There is much 
reason for believing that the gneissic and lower mica-schists form a series of overturned folds ; 
but if such folding exists, it does not extend beyond a line about eight miles from the western 
boundarv, eastward of which a succession of anticlines and synclines may be traced.* There 
are many minor local anticlines and synclines which almost abruptly appear and disappear, 
whilst even the major anticlines and synclines do not persist for very great distances. If 
an anticlinal fold is followed for a few miles it seems either to die out and be replaced by a 
synclinal fold, or to break up into minor anticlines and synclines. It may be suggested that 
this structure is due to the influence of the ancient Jurassic folding at right angles to the principal 
folds ; at any rate, a similar appearance can be very easily produced by first bending a few 
layers of soft cloth into rather open folds, and then strongly compressing the cloth in a direction 
at right angles to the primary folds. 



Period of Metamorphism. 

When strongly folded sediments exhibit what is commonly termed " dynamic meta- 
morphism," it is generally assumed that the characteristic foliation or schistosity was produced 
mainly by the lateral pressure which gave rise to the folding. On the other hand it is known 
that a high degree of fohation may be produced without notable plication. Such foliation 

* See also Bull. No. 1 (New Series), N.Z.G.S., 1906, p. 42. 



79 

has taken place in Otago, where large areas of highly schistose rocks are very gently folded.* 
It is therefore possible that the metamorphism of the lower Arahura dates back to a pre- 
folding period : and if it could be shown that the Arahura schists are the equivalents of those 
in Central Otago, this view would be greatly strengthened. The fact, however, that the very 
lowest beds— the gneissic schists-— are less schistose than the overlying mica-schists is rather 
in favour of schistosity produced during a folding period. 

If the view, apparently preferable, be adopted that metamorphism took place during 
phcation of this strata, it probably dates back mainly to the first alpine folding period, 
considered in this bulletin to have been the Early Eocene. 

Causes of Metamorphism. 
Besides the ordinary dynamic or regional metamorphism induced by conditions of pressure 
and heat prevailing over wide areas, thermal metamorphism induced by igneous masses is 
in evidence near the granite bosses and the serpentine sills. It is clear, however, that in the 
case of the Pounamu Formation hydrothermal solutions had far more effect than the mere 
heat of the igneous masses. Hydrothermal action is also probably responsible for the 
formation of certain bands of silicified schist associated with the raica-schists. The thermal 
metamorphism produced by the plutonic intrusions is of a most remarkable and interesting 
character, but a correct comprehension of its effects is difficult, owing to the complications 
produced by the accompanying and later mountain-building movements. 

Thickness of the Series. 

It is difficult to say even appro.ximately what the total thickness of the Arahura Series 
is, mainly because the extent to which overfolding has taken place in the lower and middle 
schists is uncertain. These for a distance of about eight miles, measured at right angles to 
the strike, have an almost constant dip to the south-west at high angles, and in this section show 
an apparent thickness of fully .35,000 ft. The variations in dip are so irregular as to afford 
little clue to the number of overturned folds. They do, however, tend to support the view that 
there is overfolding on a large scale. The occurrence of two distinct lines along which mag- 
nesian solutions have reached the present surface may indicate reversed faults, each accom- 
panying an overfold. Further evidence for overfolding is afforded by a comparison of the 
western limb of the first apparent syncline with the eastern, and with the limbs of the 
subsequent folds to the east. From this it would seem that the first western limb was four or 
five times as thick as the eastern limb. Though it is true that the comparison cannot alto- 
gether be relied upon — for it is an easy matter to draw diagrams disposing of the superfluous 
thickness without calling in the aid of overfolding — still, the disproportion is suggestive. 
A final argument for overfolding is its inherent probability in connection with mountain- 
building ; and it is indeed almost demanded by the mountain-building hypothesis supported 
by Suess. 

A consideration of all the factors shows that there may be two overturned folds in the 
upper and middle schists. A rough estimate based on this assumption gives 20,000 ft. to 
.30,000 ft. as the probable maximum thickness of the strata in the Arahura Series as developed 
in the Mikonui Subdivision. This estimate does not include the thickness of the beds 
belonging to the series which outcrop only on the eastern side of the main divide. On the 
other hand no allowance has been made for po.ssible thickening of the beds during folding. 

Fossils. 
Onlv in one localitv have fossils of any kind been found in the Arahura Series as it appears 
in the Mikonui Subdivision. This is on the main divide just north of Mungo Saddle, where. 



* Hutton, F. \V. : ■■ The Geological HLstory of New Zealand," Trans. N.Z. Inst, vol. xxxii, 1899, p. 163. 
Park, James : " The Geology of Cromwell Subdivision," Bull. No. 5 (New Series), N.Z.G.S., 1906, pp. 26 
and 27. 



HO 

in a dark, tough argillite, there are seen numerous tubes of siliceous material, some of which are 
smooth and straight, others curved and ribbed. 

The length of the straight tubes cannot be determined from the specimens collected, 
but is probably over 2 in. (50-8 mm.). The maximum diameter of the larger tubes is nearh' 
I in. (6--35 mm.), of the smaller specimens + in. (o-l mm.) or less. The original cross-section was 
circular, or nearly so, but many of the specimens have been compressed or otherwise distorted. 
The walls of the tubes have a thickness of one-sixth to one-tenth of the total diameter, and 
are on the outside marked with fine longitudinal striations. of which there are about sixtv in 
the complete circle. Though now siliceous, the original substance of the walls may have been 
calcareous. Plate XVIII, figs. 1-3. illustrates a number of specimens. 

The occurrence of most of the specimens in argillite indicates that the original habitat was 
mud, in which they are supposed by McKay to have lived in a vertical position. Out of twenty- 
five examples collected by the present writer only six stand vertical, or nearly so, to the strati- 
fication of the enclosing rock, whilst the others lie horizontal, or at moderate angles to the 
bedding-planes. It is certain, however, that many if not all of these latter specimens have 
been moved out of their original position. 

The fossils agree substantially with Torlessia mackayi as described by Dr. F. A. Bather,* 
to which they may therefore be referred. This annelid has been found in rocks believed to be 
of Maitai or Carboniferous age in many parts of Western Canterbury, and also near Welling- 
ton. It has also been recorded by McKay as occurring at Kelly's Creek, in the Otira district.! 

Unfortunately, by an oversight, no specimen of the curved ribbed tubes seen in situ near 
Mungo Saddle was collected. Similar tubes, however, were observed in a flat water-worn 
pebble of argillite which was found in the Hokitika River bed above the granite gorge, and 
which was certainly derived from the neighbourhood of the main di\'ide. This pebble shows 
five specimens of the fossil in question (see Plate XVIII, fig. 4, a, h), together with several 
fragments of Torlessia mackayi. The maximum length of the tubes is uncertain, but is not less 
than IJin. (31-8 mm.), whilst the greatest outside diameter is over Jin. (6-35 mm.). The 
tubes taper and are strongly curved towards one end, but these features are not well illus- 
trated in the specimens, and were seen only on splitting the pebble in which they occur. The 
tube-walls, now of .silica, may originally have been calcareous. Excluding the ribs, they 
are of no great thickness. The cross-section of the tubes (in.side the walls) was probably 
originally circular, though possibly it was slightly ovate. The ribs are well marked, and in 
number not less than twenty or more than twenty-four. 

The specimens differ from Dentalium huttoni, as described by Dr. Bather,^ in manner of 
curvature and in being moie strongly and numerously ribbed. Though presumably repre- 
senting Dentalium thev must be referred to another and probably hitherto undescribed 
species. 

Loose boulders containing the fossils just described are fairly common in the gravels 
of the Hokitika River, and indicate that, though the fossiliferous beds now outcrop over a 
very small area in the subdivision, they once had a greater extension. § 

General Petrology. 

(1.) Lower Gneisses and Schists. 

The rocks included under this title, comprising the lowest and most westerly part 

of the Arahura Series, occupy the greater part of the areas described in Chapter IV, under 

the heading of " The Granite and Gneiss Mountains," as well as portions of the low saddles 



*"The Mount Torlesse Annelid'": Geol. Mag. (N.S.), Dec. 1905, pp. 532-41. See also Geol. Mag., 
Jan., 1906, pp. 46-47. 

t "Geological Explorations of the Xorthern Part of VVestland'': .Mines Report. 1893, C.-3, p. 135. 

X Loc. cit., pp. 539^1. 

§ For further particulars concerning the annelid and list of localities in which it occurs, see McKay, " On 
the Older Sedimentary Rocks of Ashley and Amuri Counties," G.S. Rep. during 1879-80, vol. xiii, 1881, 
pp. 8t)-96. 



PLATE XVIII. 





1^^ 



.>^-^ 




Fig. 2 



/ j''. 





'^f.^ 



Fi4 4 





Fig. 3. 



a 

^ 






CL. 






CI, 



T0RLESSI.\ MACKAYI AND DeXTALIUM (?) SP. 

Fi2. 1. Seven individuals of Torlessia mackayi in grauwacke boulder. Hokitika River. 

2. Six individuals of Torlessia mackayi in argillite, near Mungo Saddle. 

3. Specimen of Torlessia mackayi showing longitudinal striations, natural size and magnified f , from 

neighbourhood of Mungo Saddle. 

4. Argillite pebble with several individuals of supposed Dentaliuvi, Hokitika River, a and &, natural 

f^ize and magnified \, showing ribs; a^ and ai represent individual a as seen on splitting the 
pebble ; c is a fragment of Torlessia mackayi. 



Geol. Bull. Xo. 6.] 



[To face page 80. 



81 

between the more prominent heights. The western boundary has already been indicated 
as that of the whole Arahura Series. The remarkable depression or line of erosion called 
Gregory Valley in this bulletin may be regarded as in a general way the eastern boundary, 
but rocks showing a transition into the adjoining mica-schist are commonly seen on the 
alpine side of the valley. The western layers are generally light-coloured, and have a coarse- 
grained gneissoid appearance, but there are highly siliceous layers of fine grain. They pass 
eastward into darker rocks, usually micaceous, but sometimes hard and tough, with little 
or no visible mica. The dark schiste pass gradually into the lower highly micaceous schists 
of the next subdivision, without any visible unconformity, and on this account they, together 
with the gneissoid rocks, have been included in the Arahura Series, though their different 
lithological character suggests that they ought to be separated from it. 

(a.) (hieissic Schists. — The gneissic*^ schists are not of very uniform character, and 
there are a number of varieties to be distinguished. Notwithstanding the general high degree 
of metamorphism. there are certain layers which seem to be of undoubted sedimentarv origin. 
Perhaps the most conunon tvpe is that which exhibits a greyish-yellow or rusty -coloured 
outcrop, and megascopicalh- shows quartz, feldspar, and mica (either biotite or muscovite, 
or both), with more or less nondescript browni to dark material, arranged in irregular bands and 
strings. Tnder the microscope feldspar is usually the most prominent mineral. It is gene- 
rally fresh, and often shows polysynthetic twinning with the extinction-angles characteristic 
of an acid soda-lime feldspar. The quartz forms irregular lenses, with mosaic structure, 
and sometimes shows slight undulose extinction. It is more often in small (|uantity than not, 
but is oc<"iHionally the predominant mineral present. A brown biotite is the principal mica, 
but exceptionally it is absent, and muscovite is then developed, often in plates of some size. 
.\mphibole is either not seen or is present only as small poorly pleochroic prisms. This type 
may be either of sedimentary or, more probably, of igneous origin. 

Another phase r)f the gneis.sic schists is a hard, bluish-white, fine-grained banded rock 
consisting almost entirely of quartz with a little muscovite. This appears principally on 
the south and east side of Mount Misery, particularly in the bed of Surveyor Creek. With this 
phase may be included a band of white granular rock with the characteristics of a compressed 
sandstone which is seen on Murrav Saddle, in the bed of Minnow Creek. These highly sili- 
ceous rocks are probably of sedimentary origin. 

X third phase presenting considerable difficulty with respect to its age and origin is 
developed conspicuouslv in the upper valleys of the Mikonui River and Doctor Oreek. It re- 
"iembles an altered holocrvstalline igneous rock, with gneissoid or schistose structure, and 
macroscopicallv sho\\s abundant feldspar and hornblende or other amphibole. with or without 
a dark mica. I'nder the microscope the feldspar is seen to consist mainly of oligoclase or 
other fairlv acid soda-lime feldspar. Some which does not show twinning may possibly be 
orthoclase. .Ml the sections made show immerous individuals with albite twinning, which 
is often combined with pericline. and occasionally with Carlsbad twinning. In some cases 
an appearance resembling microcline is developed by the simultaneous occurrence of the two 
systems of ])olvs\nthetic twinning. The twinned feldspars are usually fairly fresh, but the 
unt\nnned individuals are cloudy and saussuritized or otherwise altered. In .some sections 
silicification. partial or complete, of the feldspars is very noticeable. The amphibole shows 
strong pleochroism. varving from dark-green to light-yellow in the longitudinal sections, which 
are tlie onh- ones .seen in several of the slices, and may be generally referred to hornblende. 
In one section are seen small brown hornblendes with resorption border, imbedded in green 
amphibole.* The mica seen in most of the sections is nearh- alwavs strongly pleochroic, and 
mav be referred to biotite. As a rule, it wraps round the feldspar and quartz grains, and always 
has its cleavage-planes parallel to the schistosity. k little musco\nte in the form^of sericite 
occasionalh- appears. Quartz is commonly present in the sections, but seldom occurs in 

* See description of Section No. 6, p. 88. This feature strongly suggests that the orieinal rock was 
of a volcanic nature, 
(i— Mikonui. 



82 

abundance. It often shows undulose or strain extinction. The other minerals that occur 
include epidote, zoisite, calcite. chlorite, magnetite and other oxides of iron, ilmenite, titanite, 
rutile, garnet, apatite, zircon, and pyrite. 

The rocks just described might be termed gueissoid diorites, but the freshness of many 
of the minerals present and various other characters seem to indicate that they have been 
recrystallized, or are of secondary formation. The consideration of the microscopic characters 
in connection with the field relations leads to the conclusion that these rocks were fohated 
and recrystallized under the combined metamorphic influences of the granite intrusions and 
of the mountain- building movements. Occasionally they have subsequently been more or 
less crushed, when silicification generally becomes quite pronounced. No trustworthy e\-idence 
of their original nature can be brought forward, but various characters, including the abund- 
ance of leucoxeue and titaniferous magnetite, and the presence of zircons and apatite, are 
thought to indicate a primary igneous origin. 

A fourth phase of the gneissoid rocks is represented by narrow layers of rather fine- 
grained grey rock which occur interbanded with the coarse portions, and may be of sedimen- 
tary origin, though the microscopic examination of several sections has thrown much doubt on 
this view. 

In several places, notably on Mount Bonar, the gneissic schists contain bands of altered 
grauwacke, which do not exhibit schistose structure to any extent. These are possibly fault- 
involved beds of a younger formation. 

The gneissic schists contain in places numerous basic dykes, which will be described 
in Chapter XIII. Only a few acidic dykes of such a character as to indicate genetic connec- 
tion with the neighbouring granite bosses were observed. 

The age and origin of the primarily igneous portions of the gneissic schists must for the 
present be regarded as uncertain. Though it was at first supposed that these rocks represented 
dykes connected with, the Tuhua Formation, or derived from the same magma, no convincing 
e\adence in favour of the assumption could be obtained. The bulk of the data afforded by 
the field and microscopic examinations supports the view that they are of pre-Tuhua age. 
The chief facts tending towards this conclusion are a varying chemical composition, whicl 
always decidedly differs from that of the Tuhua rocks, and the recrvstalUzation, apparentlv 
due to the metamorphic influence of the granitic intrusions, which has taken place. It may 
be that the rocks in question owe their origin to igneous action contemporaneous with the 
deposition of the lowest beds of the Arahura Series. The presence, in the overlying dark 
schists, of belts which appear to be of volcanic origin is in harmony with this view, and may 
be considered as indicating a period of vulcanism of considerable duration. 

(b.) Dark Schists. — These form a band of. perhaps, 1.000 ft. in thickness between the 
gneissic schists and the mica-schists of the next division. They are probably largely of igneous 
origin, and one shghtly schistose band of a dark-greenish ijolour without any sign of strati- 
fication seems to represent an old igneous rock of andesitic character (see " Special Petrology," 
No. 12, page 91). This band is seen at intervals from the second gorge of the Tuke River to 
Evans Saddle. 

The dark schists are less siliceous than the mica -schists, and often contain numerous 
garnets. In places they are much spotted from the secondary development of triclinic feld- 
spars. Towards the line where they pass into lighter-coloured micaceous schists they often 
exhibit, between fairly parallel foliation-planes, a number of fine layers with highly contorted 
structure. Occasionally they present a decidedly serpentinous character. 

Under the microscope the sections exhibit much feldspar, sometimes in well-developed 
crystals ; at other times broken or with irregular outlines. It is occasionally polysynthetically 
twinned, both on the albite and pericline laws, and may then be oligoclase or andesine. In 
one or two sections secondary orthoclase (valencianite) may be present, but the identification 
is very doubtful. Biotite is not very plentiful, and is almost absent from one section. Quartz 
Ls, as a rule, present in small quantity. Epidote is, however, abundant, and other constituents 



83 

are garnet, hornblende and other amphiboles, titaniferous magnetite, leucoxenic titanite, 
calcite, chlorite, pyrite, a nearly isotropic clear mineral which occurs in irregular patches 
and strings (probably serpentine), and possibly M-ollastonite, Brown or dark strings of in- 
determinate character are plentiful in all the sections. 

Localities where tiie dark schists may be studied are : Mount Hany (Up})er Kokatahi 
district), the lower course of Vanina Stream (a tributary of Doctor Creek), the vallev of 
Douglas Stream, and Hende's (on the western side of the Wanganui River). 

(2.) Mica-schists. 

The mica-schists and associated rocks may be divided according to lithological characters 
into— (o) Quartz-mica-schists ; (b) (juartz-schists ; (c) phyllifes : (d) doubly metamorphosed 
rocks, affected not only by regional metamorphism. but also by neighbourhood of the Pou- 
namu Formation, or bv hvdrothermal solutions arising therefrom. 

(o.) Quarlz-mica-schisis. — The schists which come under this heading form the great 
bulk of the second subdivision of the .Arahura Series. Megascopicallv thev can be distinguished 
from the gneisses and dark schists by their almost uniform light-grey to medium-grey colour 
and the more fully developed schistosity. with characteristic micaceous glimmer. Under the 
microscope green hornblende is absent, and feldspar rare, whereas these minerals are com- 
monly present in the gneissic schists. Typical specimens consist almost entirely of quartz 
and mica, with quite subordinate amounts of other minerals. 

The (|uartz-mica-schists may he subdi^^ded into several varieties, hut these are litho 
logically similar, and graduate into one another. The chief difference lies really in the lessening 
degree of schistosity and general metamorphism as they are followed from lower to higher 
horizons. The following varieties, however, mav be enumerated : Quartz-biotite-schist, 
quartz-sericite-liiotite-schist, quartz-garnet- biotite-schist, mica-quartz-schist, artinolite-hiotite- 
quartz-schist. and chloritic quartz-schist. 

The quartz-l)iotite-schists exhibit conspicuous flakes and spots of biotite, scattered along 
the well-developed foliation-planes. The mass of the rock consists of layers of quartz and 
biotite, with some sericite. Quartz is the most abundant mineral, forming, as a rule, over 
one-half by bulk of the rock. The accessorv minerals are garnet and zircon, with occasional 
epidote or zoisite. Sometimes a few partly sihcified feldspar grains may be observed. 

The quartz-sericite-biotite-schists differ from the preceding variety only in the absence 
of the conspicuous biotite flakes, and perhaps a slightly greater development of sericite. 

In the quartz-garnet- biotite-schist numerous garnets are macroscopically developed, and 
in some bands may form the principal mineral. Rocks of this class occur principally in 
the lower horizons of the mica-schists. 

In what may be called mica-t|uartz-schists, quartz largely predominates over mica, both 
macroscopically and microscopically, and schistosity is not so perfectly developed as in the 
biotite-schists. Schists of this character especially characterize the upper schists above 
the horizon of the Pounamu Formation. They are hard and tough, whilst lamination-planes 
are rather poorly developed, so that the rock does not split well. The silicified feldspars 
occasionally seen in these schists may have originally developed under the influence of the 
Pounamu intrusions, but more probably represent primary grains. 

The actinolite-biotite-quartz-schists have a very Umited extension. In them idiomoiphic 
actinolite is developed in some abundance, and fjuartz largely exceeds biotite in quantity. 
Thev ought perhaps to be referred to group (d), but are mentioned here because in part at least 
they are not known to be connected with the Pounamu Formarion. Epidote is probably always 
present. 

The chloritic quartz-schists are not of frequent occurrence. They consist of quartz 
folise, with more or less chlorite. Those with a high percentage of chlorite may be referred tc 
group {d). 

6" — Mikonui, 



84 

(6.) Quartz-schists. — Certain light-coloured bands in the middle and upper schists, more 
especially near the horizon of the Pounamu Formation, which consist almost entirely of 
quartz, and have apparently been silicified by the agenc}- of liydrothermal solutions, may be 
described under this heading. They graduate into quartz-mica-schists. 

(c.) PhylUtes. — The distinction between the biotite-schists and the phylUtes is a verv- 
small one, consisting mainly in a finer micro -structure and a less degree of metamorphism. 
The phylUtes found in the Mikonui Subdivision may be placed in two classes. One of 
these forms a belt west of that in which the Pounamu Formation occurs, and outcrops on 
Jumbletop, Mount Bowen, &c. It is characterized by its fine grain and perfect fissility, 
which leads to its ready weathering. The lessened metamorphism as compared with the 
schists on either side may be due partly to its original finer grain, partly to its having 
been exposed to less heat and pressure than the underlying schists, while at the same time 
free from the influence of the magnesian solutions which have affected the schists of the 
Pounamu belt. 

The second class of phyllite occurs east of the Poimamu rocks, in bands alternating with 
the rocks described as mica- quartz-schists. It is fissile and generally friable, but the lami- 
nation-planes are less regular and uniform than those of the western belt. 

{d.) Doubly Metamorphosed Rocks. — Under this heading comes a considerable variety of 
schists, which owe their characters to thermal metamorphism induced by the Pounamu For- 
mation and the accompanpng heated solutions, either superimposed upon regional meta- 
morphism, or preceding it, the former being far the more likely supposition. To these schists 
must be added one or two rocks which, though j^robably formed in connection with the 
serpentine intrusions, are not seen in the vicinity of any outcrop. The chief varieties of 
metamorphic rock now to be described are the following : Talc-schist, chlorite-schist, and 
amphibole-quartz-schist. 

The talc-schists occur in bands of from a few feet to 200 ft. or more in width, either 
actually in contact with serpentine outcrops, as continuations of serpentine bands, or as 
rather persistent bands parallel to the Pounamu belt, but at some distance from it. The 
talc-schist bands are very numerous in the Toaroha Survey District, and in the north-west 
corner of the Murraj' Survey District, but south of Cropp River they all but disappear, 
reappearing only as a very small outcrop in the valley of the Waitaha River near a minor 
isolated mass of serpentine. The talc-schist bands were very carefully followed, and all of any 
consequence are indicated on the maps accompanying this report. 

In one place — near the first gorge of the Kokatahi River — the talc-schists appear as a wide 
band of almost pure silvery-green talc, beautifully laminated, and in thin flakes semi-trans- 
parent. Generally, however, the talc-schist bands contain a good deal of quartz, sometimes 
in laminfe, sometimes in large segregated masses. They also often show narrow layers of 
almost unaltered mica-quartz-schist, which by the addition of talc, and eUmination of quartz 
and mica, pass almost imperceptibly inrci talc-schist. The bands in contact with serpentine 
show on weathering numerous fragments of hackly honeycombed quartz, which appear to be 
the remains of larger pieces corroded by the thermal solutions which have given rise to the 
talcose material. Near the serpentine outcrops the talc-schists may contain octahedrons of 
magnetite or cubes of pyrite, or both. Magnetite crystals especially often weather out in 
great quantity. 

WTiilst, as will be gathered from the general description, the talc-schist bands generally 
follow the stratification of the original schists, in at least two cases they bend and follow 
fault-lines or crush zones, crossing the beds at an acute angle. The examples referred to occur 
in Harry and Brow creeks, the former of which is on the east and the latter on the west side 
of the Whitcombe. 

The chlorite-schist bands are found principallv in contact with the rocks of the Pounamu 
Formation. When occurring in this connection they consist mainly of chlorite, with a little 
quartz, and idiomorphic crystals of pyrite, with or without octahedrons of magnetite. The 



85 

pyrite crystals were originally cubes, but these are often greatly distorted by pressure, and 
have acquired a hardness almost or quite equal to that of quartz. 

The amphibole-quartz-schists consist largely of quartz, with more or less amphibole 
in the form of tremolite, actinoUte, or hornblende. They occur in narrow bands, one of which 
was located in the bed of .JuUus t^reek, a small tributary of the Waitaha ; whilst another occurs 
near the top of Mount VVilberg, on the south side of the Wanganui. A wider band than either 
of these crosses Wilberg Stream, a southern branch of the Wanganui. The two last-men- 
tioned bauds are several miles from any known outcrop of the Pounamu Formation. 

(3.) Less Altered Grauwackes and ArgHlites. 

The area occupied by the rocks under this head extends from a somewhat arbitrary 
line eastward to the main divide. The average width of the belt within the subdivision 
is about three or four miles, but it extends far to the east into Canterbury. The rocks 
included may be discussed under the headings of— (a) Subschistose rocks, (b) non-schistose 
rocks. 

(a.) Siibschinlose Rocks. — The subschistose rocks which succeed the schists consist of 
grauwackes and argillites. The grauwackes form a rather thick belt immediately to the 
east of the somewhat indefinite Une chosen to separate schists from non-schists. They are 
dark-coloured rocks, often rather coarse-grained and harsh to the touch, and in many places 
strongly jointed. The finer-grained varieties and fault-crushed bands show more or less mica 
along the parting planes, but very often schistosity is indicated only by a flattening of the 
individual grains. (Jwing to the poor development of the bedding-planes the strike and dip 
are very commonly difficult to determine. The difficulty is increased when, as is often the 
case, they are shattered by faulting. They contain numerous small quartz veins ^ in. to J in. 
thick, which either lie along the bedding-planes or cross them at small angles. Sometimes 
there is a second system of small veins at right angles to the first. 

The grauwackes just described are succeeded by a thick belt, in which fine-grained grau- 
wackes alternate with still finer bands, which, though generally not of so fine a texture as 
typical argillites, may be called by this name. These argillites are dark-coloured and noticeably 
schistose to the eye. They exhibit good bedding-planes, and in many places might be called 
slates, but have no slaty cleavage. Microscopically they are seen to consist of the same 
minerals as the grauwackes — that is, quartz, acid feldspars, biotite, muscovite, &c. 

As shown in the Hokitika Bulletin, the sediments of this and the overlying part of the 
.\rahura Series have probably been derived from an ancient granitic or gneissic area.* 

(6.) Xon -schistose Rocks. — The subschistose grauwackes and argilUtes gradually lose 
megascopic schistosity or foliation as they approach the main divide, but the belt that comes 
under this heading is not a very wide one, and towards the south of the subdivision tends 
to become narrower, or even to pass to the east of the main divide. In the Mikonui area it 
. consists principally of grey or dark grauwackes, with subordinate bands of black argilUte. 
About the crest of the main divide the grauwackes are light in colour, owing to the predominance 
of quartz as a constituent, and in places may be called quartzites. 

X curious phase of the grauv\ackes is one in which angular pieces of black argillite of all 
sizes are seen to be embedded in the lighter, coarser-grained rock. These are often so 
numerous as to give the grauwacke a breccia-hke appearance. As an explanation of the 
formation of this tvpe, it has been suggested " that the beds of coarser sediment, while in course 
of formation on the sea-floor, received fragments from beds of hardened mud close by, dis- 
rupted by the sea-wave3."t Microscopically the grauwackes and argilUtes consist of exactly 
the same minerals as the underlying subschistose rocks, and have evidently been formed by 
the waste of the same land-area. 



* Bull. No. 1 (New Series), N.Z.G.S., 1906, p. 4tj. f Loc. cit., p. 45. 



m 

Special Petrology. 
IJnder this heading a description, either brief or detailed, as the occasion warrants, will 
l)e given of various rocks included in the Arahiira Series which \\ere microscopicall}' examined, 
but if time and space permitted many of these descriptions might be greatly elaborated. 

(1.) G^neissic and Dark Schists. 
(1.) From near the head of Totara River. 

The hand-specimen is a somewhat banded gneissic-looking rock, -which, when broken 
across the grain, shows badly defined layers of alternating dark and hght colour. The fracture 
is irregular. The most noticeable mineral is amphibole, which occurs in large crystals having 
their longer dimensions parallel to the banding, but otherwise irregularly disposed. By 
careful examination of the fractured surfaces a rather poorly developed prismatic cleavage with 
the angle characteristic of hornblende, and a cleavage at about right angles to the j^rismatic, 
may be observed. There are numerous small to medium-sized feldspars, with greasy lustre, 
embedded in a light-coloured matrix. A little quartz appears to be present. 

Under the microscope the section consists of feldspar, hornblende, quartz, biotite, rutile, 
chlorite, epidote, zoisite or clinozoisite, titaniferous magnetite or ilmenite, leucoxene or 
secondarv titanite, a few very small probable zircons, and possibly a little apatite. The general 
structure is allotriomorphic, one mineral being often moulded upon another, and it caiuiot 
be said that there is any very definite order of crystalUzation, except that hornblende comes 
more often before than after feldspar, and quartz seems to have been the last mineral to 
form. 

The feldspars are to some extent idiomorphic, but incline to show rounded angles, and are 
so surrounded b\- bands of cloudy matter and secondary products that it is difficult to define 
their exact relationship to the general structure. On this account the structure is hardly 
granitic. Most of the feldspar is untwinned, with moderately low polarization colours, and 
might be taken for orthoclase. Cleavage is not apparent. The orthoclastic feldspars show 
numerous small patches of epidote, amphibole, and other alteration-products, whilst their 
margins are also afEected by decoitiposition, with quartz as the most prominent secondary 
mineral. The ab.sence of sericite and the presence of epidote among the decomposition- 
products render it probable that these feldspars are really acid soda-lime feldspars, which 
have lost their original twinning. The other feldspars are twinned according to both the 
albite and pericline laws, the former type being the more common. Their index of refrac- 
tion is slightly higher than that of the cementing medium : they show rather low double 
refraction, and from the extinction-angles observed on the twinning-axis (7°/14° : 7°/17°) 
appear to be basic oligoclase. These feldspars are slightly epidotized, but are otherwise 
fairly fresh. 

The hornblende possesses strong pleochroism, ranging from dark-green and bluish-green 
to various shades of greenish -yellow. Inclusions and bays of feldspar are common. 

The quartz is in irregular patches, composed of a number of individuals, all the larger 
of which show undulose or strain extinction. From its habit it appears to be secondary-. It 
occurs also as a fine mosaic resulting from the decomposition of feldspar. 

Biotite occurs sparingly, is brown or green, and strongly pleochroic. It often contains 
sagenitic needles of rutile. Some has decomposed to chlorite. 

Epidote is fairly abundant in small granules throughout the matrix, and, as mentioned, 
in the feldspars. A small vein of epidote which traverses the whole section shows a charac- 
teristic pale-yellow colour, and noticeable pleochroism. 

A few small crystals, considered to be zoisite from the low interference colours, ought 
perhaps to be called clinozoisite (colourless epidote, low in iron). 

Titaniferous magnetite, or more probably ilmenite, is common in small grains, each sur- 
rounded by leucoxenic products, which maj' in the main be referred to titanite. Quite often 
the original mineral has altogether disappeared. 



87 

Remarks. — No very definite name can be given to this rock. It may be called horn- 
blende-gneiss. Though po.ssibly the orthoclastic feldspars are original, it has probably been 
almost or entirely reconstructed under the mfluence of heat and pressure during the mountain- 
building and granite-intrusion period. It may be by some more or less doubtfully considered 
as a slightly gneissic phase of less acidic rock occurring around the margin of the granite 
bosses, and called gneissose biotite-hornblende-diorite or some similar name. The great 
overthrust plane of the Southern Alps is just to the west of the outcrop, and granite 
appeal's a short distance to the east. Compare the description given of this rock with those 
of Nos. 2, ."i. 4, &e. 

(2.) From same locality as Nd. 1, near the head of the Totara River, but higher up the 
stream. 

The hand-specimen has the appearance of a dark coarse-grained syenite or diorite, with 
incipient gneissoid structure. Feldspar is abundant in crystals of somewhat irregular shape, 
but often with one oi- more rectilinear boundaries. A little quartz is seen to be present, 
associated with the feldspar. Abundant amphibole and biotite in more or less connected 
patches of very irregular outline make up more than lialf the specimen. The rock effervesces 
in the cold with hydrochloric acid. 

I'nder the microscope the minerals present are found to be feldspar, hornblende, biotite, 
rutile, (juaitz, epidote, zoisite or dinozoisite, titaniferous magnetite, leucoxenic titanite, apatite, 
and calcitc. The .structure is apparently granitic. 

Some of the feldspar is much decomposed and uiitwinned, and may originally have been 
any of the more acid species, but the greater part, if not all. may be referred to basic 
oligocla.se. .-Vlbite, pericline, and Carlsbad twinning are all present. 

The hornblende is strongly pleochroic, the colour varying fiom bluish-green to yellow. 
It is somewhat moulded bv feldspar, and contains a few small patches of that mineral, as well 
as numerous grains of magnetite. 

Biotite is very plentiful, with characteristic pleochroism. The individuals are fi-equently 
Ix'iit and drawn out. Inclusions of rutile needles are common. 

Quartz is not very common, and usually shows undulose extinction. 

Some clearly secondary (|uartz is present, arising from decomposition of feldspar, &c. 
It occurs in small patches, composed of several individuals. 

A few small crystals with high inde.v of refraction are almost certainly titanite. 

\ little epidote appears as a secondary product in small grains here and there, especially 
in the decomposed feldspars. 

Zoisite supposed to be present may be dinozoisite. 

Magnetite occurs in numerous irregular grains, associated chiefly with the hornblende. 
Its titaniferous character is shown by its frequent association with leucoxenic products. 

A goofl deal of leucoxenic or secondary titanite appears throughout the section, as well as 
associated with the titaniferous magnetite. 

There are one or two patches of calcite. with characteristic absorption and cleavage, in 
the section. 

Remarks.— Th<^ rock might be called a slightly gneissoid quartz-biotite-hornblende-diorite, 
but is here regarded as lia\ing assumed its present state of crystallization through metamorphic 
influences, without passing through a state of fusion. Prior to the mountain-building periods 
it mav have possessed the characters of a true igneous rock. 

(3.) From outcrop U chains above Doctor Creek Waterfall. 

The hand-spedmen appears to be a biotite-granite (granitit*). which contains numerous 

grains of a red ganiet. 

Under the microscope the section exhibits soda-lime feldspars of probably more than 
one species, biotite, amphibole, quartz, garnet, magnetite, apatite, rutile, zircon(?), epidote, and 



88 

p}Tite. There is considerable evidence of strain and movement in several of the constituent 
minerals. 

The rock inightf be. ^called anT altered hornblende- biotite-granite (homblende-granitite), 
but the section exhibits**;manyrpeculiar characters difficult of explanation. There is much 
reason for believing that the rock has been crushed, and then almost wholly recrystallized. 
It lias therefore been decided to include it with the metamorphic rocks. 

(4.) From upper end of Smith Gorge, Doctor Creek. 

The hand-specimen shows a dark surface, mottled with white spots. The structure 
is_ slightly schistose, and in the original outcrop contortion is very evident. Biotite, probable 
amphibole, and some form of feldspar are macroscopically evident. 

Under the microscope it is seen to consist of feldspar, hornblende, biotite, magnetite, 
p\rite, and epidote, with small crystals of rutile, apatite, and perhaps other minerals, including 
zircon. Schistosity is not very apparent. There is a decided tendency, as in several other 
sections of the series, for the various larger indi^'iduals to be separated by strings of kaolinitic 
matter and other impurities. 

The feldspar is moderately fresh, and twinned on both the albite and pericline laws. Some 
is probablv acid labradorite ; the rest may be oligoclase or andesine. The crystals are often 
bordered by a decomposition ring, consisting principally of epidote, and usually contain a few 
amphibolic needles, some of which show good pleochroism. 

Hornblende is abundant in large crystals, with dark-green to greenish-yellow pleochroism. 
It has an idiomorphic habit, and shows occasional twinning. 

The biotite has the usual strong pleochroism, dark-brown to light-yellow\ Small secondary 
amphibole needles are developed in the biotite. 

Magnetite is plentiful in sha^jeless masses, in some of which a little pyrite is embedded. 

Epidote is present in small grains, and as a vein crossing the section. 

Presumably the rock must be called a biotite-hornblende-feldspar-schist, or, apart from 
the field relations, it might be designated a schistose hornblende-diorite. According to the 
view adopted in this bulletin, it is a recrystallized doubtfully igneous rock, forming part of 
the metamorphic complex separating the undoubted acid plutonics from the mica-schists of 
the Arahura Series. 

(5.) From Open Creek, a tributary of the Upper Mikonui, draining slopes of Fraser Peak. 

The hand-specimen is a coarse-grained somewhat gneissic rock, exhibiting biotite, feldspar, 
and quartz as its main constituents. 

Under the microscope the section is seen to consist of feldspar (oligoclase), quartz (much 
of which represents crushed and silicified feldspars), biotite with rutile needles, a little sericitio 
muscovite, epidote, pyrite, haematite formed by decomposition of the pyrite, and a few small 
zircons. The structure is typically schistose. (Plate XX, No. 1.) 

The rock may be called a feldspathic biotite-schist. It would seem that after the original 
rock had been rendered schistose and recrvstalUzed it was subjected to further movement, 
which crushed some of the feld.spars, and was' followed by partial silicification. An analysis 
is given at the end of this section. 

(6.) From Headover Creek, a tributary of the Mikonui, draining part of Fraser Peak. 

The hand-specimen is a gneissoid rock, with alternating dark and hght bands, the former 
mainly biotite, the latter largely quartz with apparently a little feldspar. 

Under the microscope the chief minerals present are seen to be feldspar, quartz, biotite, 
and garnet. The other constituents are amphibole, rutile, magnetite, a few small zircons,jrand 
dark strings of nondescript or amorphous material. (Plate XX, No. 2.) 

The feldspar, probably all plagioclase, is fairly fresh, but the larger grains are affected 
by formation of small secondary amphiboles, &c., along cleavage planes. Many of these 




E~i 



b S 

o t: 



o •- 
o :; 



89 

grains do not ahow noticeable twinning, but in others albite, pericline, and traces of Carlsbad 
twimiingjmay be detected. These from the extinction-angles are probably oligoclase, but a 
more basic feldspar may also be present. 

There are in one part of the section several large amphiboles with pale-green to greenish - 
yellow _pleochroism and extinction at 8°. In one individual several small brown crystals of 
hornblende with resorption border are embedded. Some of the amphiboles and biotites con- 
tain sagenitic rutile, and many excessively fine needles throughout the feldspars are also 
referable to rutile. 

The quartz is in bands often wrappmg round the larger feldspars, which show a most 
irregular interlocking mosaic structure, similar to that seen in various other sections of the 
series. Some of the individual grains show slightly irregular ex-tinction under crossed nicols. 

Biotite is not very plentiful ni the section, which happens to include only one dark band. 

The garnets are shattered, and the individual grains are often moved along the planes 
of schistosity— that is, they are not liattened, but separated from one another. The inter- 
vening spaces are tilled with quartz and biotite. 

An analysis of the rock is given at the end of this chapter. 

(7.) From the Upper Mikonui Valley, above junction with Dickson River. 

The hand-specimen is a dark schistose rock with contorted structure. A dark mica 
appears the most abundant muieral to the miaided eye. There are also some black amphibole, 
quartz, &c. The rock effervesces rather freely with acid. 

Under the microscope the structure is strongly schistose, the mica in particular being 
drawn out or arranged in long bands. 

Green hornblende, with the pleochroism previously noted, is perhaps the most abundant 
mineral. It has very irregular outlines, and apparently is much broken up. 

There is abundant biotite of the usual character, some quartz in UTegular ftne mosaics, 
with undulose extinction in the larger grains, a fair amount of epidote, some clinozoisite, 
abundant calcite, altered magnetite (with dull black? surface), and possibly- one or two small 
zircons. No feldspar can be detected, but a few of the quartz grains probably represent siliciiied 
feldspars. A little sphene is probably present. 

The rock may be called a hornblende-biotite-schist. It has recrystallized under the 
influence of heat and pressure, while at the same time being drawn out and rendered schistose. 

(8.) From the upper part of Doctor Creek (exact locahty unknown). 

The hand-specimen is a dark, fairly fine-grained, mdurated rock resembUng a grauwacke, 
with" apparently subscliistose structure. 

Under the microscope the section exhibits a most characteristic, strongly schistose struc- 
ture, well seen in ordinary light, thus showing that the appearance to the unaided eye of only 
moderate schist-osity was deceptive. The most proruinent mineral is quartz, partlv in small 
rounded grains, partly in finely crushed drawn-out bands. Some of the grains are only partly 
crushed, and a few are merely cracked. Under crossed nicols the whole grains nearh all 
extinguish normally, the crushed material shows as a fine mosaic, the partlv crushed grains 
usually exhibit undulose extinction. Probably a great many of these quartz grains represent 
silicified feldspars. .\n occasional grain shows feldspar cleavage or traces of twinning, &c. ; 
these are partly silicified feldspars. One grain shows good albite twinning. 

The other constituents of the section are biotite, amphibole (rare), a little epidote, magne- 
tite, and pjTite, with nearly opaque brow n and white nondescript matter, an-anged in well- 
defined lines curving round the quartz grains. The biotite is in small fragments, or, with 
other minerals, is drawn out into long strings which wrap round the quartz granules. 

This rock, evidently originally a grauwacke, is now a very decided biotite-schist ; but 
it is quite different from the biotite-schists of the next division, where the quartz is wholly 
secondary. Though it has been subjected to great pressure, yet the conditions have not 
altogether favoured the processes which result in the formation of a typical mica-schist. 



90 

(9.) From creek on west side of Hokitika River, 17 chains south of the granite gorge, 
near granite contact. 

The hand-specimen is a fine, close-grained grey rock with a somewhat banded or schistose 
structure. As occurring in the field it seemed to be more or less bedded, and resembled an 
altered sedimentary rock. 

Under the microscope the section is seen to represent a highly altered rock, consisting of 
biotite (less pleochroic than usual), possibly some sericitic muscovite, amphibole. feldspar(0. 
titaniferous magnetite, and possibly iknenite : leucoxene and titanite, apatite, possible small 
zircons, a very little chlorite, some rather doubtful epidote, pyrite, kaolinitic matter, &c. The 
structure presented is an indefinite mosaic, with a slight suggestion of schistositv. 

Biotite is in ragged masses, w hicli are more or less bleached and slightly chloritic. These 
appear to be original, but there are numerous small laths and patches of clearly secondary 
growth. 

The chief amphibolic mineral is in small, scattered laths of yellowish or greenish colour, 
mth slight pleochroism, and is clearly secondary. A little uralite, representing an original 
pyroxene, seems also to be present. 

A clear mineral considered to he a feldspar fills the spaces between the biotite patches, 
&c. There are no crystal outlines or evidence of twinning, but the substance has the double 
refraction and general appearance of a feldspathic mineral. 

Quartz is fairly plentiful in irregular grains and patclies, which show more or less strain 
extinction. 

Titaniferous magnetite and probably ilmenite are plentiful in the section. These minerals 
show dull surfaces, doubtless due to partial alteration, and are invariablv surrounded and pene- 
trated by leucoxene, either opaque or transparent enough to present the characters of titanite. 
There are numerous patches of leucoxenic titanite. one of which shows distinct twinning, 
without any residual ilmenite. as well as a rather poor rhomboid embedded in quartz which 
may represent original titanite. 

Apatite is rather plentiful in small, well-defined crystals, some of which are cracked and 
slightly bent. 

The other minerals do not call for notice. 

Remarks. — The highly decomposed nature of this rock makes it difficult to say anything 
about its original nature, but the unusual amount of titanium minerals and other features 
suggest that it was once an igneous rock. The absence of well-marked schistositv shows that 
it was not subjected to any great dynamic movement after completion of the metamorphism 
due to the neighbouring granite intrusion. 

(10.) From Gorge Creek, west slope of Mount Miserv. 

The hand-specimen is a light greenish-grev rock, with alternating bands of paler and 
darker colour. The rock locally varies much in grain, some parts showing coarse blebf? of 
feldspar and quartz. 

The section is cut from the finer-grained rock, and under the microscope is seen to consist 
of feldspar, quartz, epidote. kaolinitic matter, and a little pyrite. The structure is typically 
schistose. (Plate XX. No. 3.) 

The feldspar forms eyes in the schistose groundmass. Some is more or less broken, 
and practically all the grains are rounded. By the extinction-angles and double refraction 
it seems to be oUgoclase, but possibly a more basic feldspar is also present. Many of the feld- 
spars are well twinned, principally on the albite law, but pericline twinning is also seen. Some 
individuals are bent, and sho\\- a kind of strain extinction whilst many are more or less siUcified. 
The quartz is in grains replacing feldspar, or in veins and strings wath fine mosaic structure, 
which may well represent broken-down and silicified feldspar. Epidote is very plentiful in con- 
tinuous bands or veins, but seldom appears in the feldspars. Almost opaque kaolinitic matter, 
white by reflected light, is plentiful, and, with the epidote, is arranged in strings, which give 
tlie rock its schistose appearance. 



91 

Remarks. —The rock may be called a quartz-feldspar-schist, and was evidently once 
almost wholly composed of feldspar. Had there been any quartz at this stage it would have 
survived with the feldspar. Whether this feldspar stage represented the original rock or 
not is doubtful. Microscopically the rock rather resembles No. 5 in structure, in the presence 
of feldspar eyes, nature of secondary quartz, &c., but biotite is absent. The hand-specimens, 
however, are very difEerent. 

(11.) From second gorge of Tuke River. 

The hand-specimen is a dark, decidedly schistose rock, showing slight micaceous lustre 
on cleavage surfaces. It effervesces along some of the lighter bands on application of cold 
dilute hydrochloric acid. 

Tnder the microscope the structure is seen to be highly schistose. The minerals present 
are feldspar, biotitic mica, quartz, amphibole, epidote, calcite, and magnetite. 

Feldspar, which is perhaps the only original mineral present, appears as rounded eyes 
in the schisto.se groundmass. Some shows traces of twinning, and from the weak polarisation 
colour and extinction-angle may be judged to be an acid plagioclase. The untwinned feldspar 
may be of the same species, but it is difficult to tell. The individuals are generally silicified 
round the edges, and often contain irregular quartz grains, whilst small crystals of amphibole 
with rather feeble pleochroisra are distributed through the mass, apparently along cleavage 
planes, together with some epidote. A biotitic mica with weak pleochroism is the most plenti- 
ful mineral in the section, forming wide irregular stripes fi-om end to end. (Quartz is plentifully 
distributed through the section in small irregular grains, evidently secondary, and is also 
seen replacing the feldspars, as noted above. Epidote in irregular veins is fairly common. 
A little calcite is present, sometimes showing characteristic cleavage. 

Magnetite (? titaniferous) is not plentiful. 

The rock might be called (juartz-feldspar-biotite-schist. It is some distance from any 
granite outcrop, and proliably beyond the strongly metamorphic aureole of the plutonic 
intnisions. Mav it be concluded from the mode in which the feldspar occurs that it was 
originallv an igneous rock '. From the analysis of this rock given at the end of this .section 
it will be noticed that the silica percentage is that of an andesite, or other rock of medium 
acidity. 

(12.) From near second gorge of Tuke River. 

The hand-specimen is a dark-coloured rock, close-grained and tough, without any visible 
schistosity. It effervesces somewhat with acid. 

Under the microscope the rock is seen to be much altered, but the appearance nevertheless 
suggests an igneous rock of ])or|)hyritic facies. (Plate XX, No. 4.) 

The minerals now present are plagioclase, biotite. a colourless amphibole, chlorite, quartz, 
titaniferous magnetite, leucoxene, pyrite, possibly a little serpentine, and miscellaneous 
opaque or nearly opa(|ue matter. 

The plagioclase is in the form of fair-sized laths, often not very well defined, more espe- 
ciallv at the extremities. It is more or less twinned, and sometimes has zonary structure, 
the centre generally showing a smaller extinction -angle than the outside. The extinction- 
angles and the interference colours indicate oligoclase, andesine, and perhaps acid iabra- 
dorite. 

Onlv a little biotite is present in the section. 

Rather large areas of the section, which by their outUne suggest former porpiiyritic 
crystals, now consist almost wholly of prisms of a colourless amphibole having extinction 
"up to 20° (probably tremolit«), with some calcite. Other similar areas seem to consist of 
chlorite, quartz, &c. 

Magnetite in small irregular grains is abundant. It is no doubt titaniferous, since a 
little leucoxene occurs. 



92 

A little serpentine may be present here and there in association with the amphibole. 

Pyrite is a noticeable but not abundant constituent. 

Remarks. — Both frona the field phenomena and from microscopic examination this rock- 
is thought to have been originally igneous. Xot iruprobably it was an andesite, and this 
view is confirmed b}- the analysis given at the end of this section. 

(13.) From Bo'sun Creek (a tributary of the Kakapotahi). 

The hand-specimeu is a dark schistose rock mth small white spots, which effervesces 
on application of hydrochloric acid. 

Under the microscope the section exhibits the following minerals. Feldspar,^ biotite, 
epidote, quartz, calcite, and minor constituents. Schistose structure is not very strongly 
developed, but is indicated b}- a tendency of the smaller grains to have their longer axes 
parallel. 

The feldspar is in large grains, some of which exhibit rather faint polysynthetic twinning. 
The indi^dduals are much decomposed, and cannot be determined ^nth certainty, but are of 
fairly acid type, probably basic oligoclase. Epidote, quartz, and calcite are present as altera- 
tion-products. 

Biotite is seen in numerous small, poorly developed patches. 

Epidote is plentiful around the feldspars, and in certain areas which may represent wholly 
decomposed feldspars. 

A few grains of what may be original quartz are present in addition to that formed by 
the alteration of the feldspars. 

This rock was apparently originally an igneous rock in which feldspar predominated. 

(14.) From Douglas Creek (south side of Waitaha River). 

The hand-specimen is a dark-grey rock, with numerous dark spots of an amphibolic 
mineral and a few white patches. Schistosity seems but slightly developed. 

Under the microscope the section is seen to consist of hornblende, feldspar, epidote, 
calcite, biotite. quartz, chlorite, altered titanifeious magnetite, leucoxene, pyrite, &c. Schis- 
tosity is more apparent than in the hand-specimen. 

Hornblende is in large crystals, often broken up by mechanical movements, as well as 
to some extent by decomposition. It exhibits the pleochroism usual in the rocks of the 
gneissic series (bluish -green, light-green, greenish-yellow). 

Feldspar is also abundant in much decomposed individuals, in \\hich calcite, quartz, 
and epidote seem to be the most prominent alteration -products. Some of the feldspars still 
show traces of albite t\nnning, and one rather well-preserved specimen is a Carlsbad twin as 
well. The extinction-angles seem sufRcientlv definite to warrant its being called andesine. 
One feldspar encloses a grain of quartz, which may be original. 

The other minerals present are all secondary, epidote, pyrite, and calcite being the most 
abundant. Leucoxene in the form of poorly transparent bro\\Ti grains occurs occasionally. 

Remarks. — Presumably this rock was originally an igneous rock : in that case it was 
probably holo-crystalline, and may have been a diorite. Such would be the most likely con- 
clusion from the examination of the hand-specimen and section alone. The field relations, 
however, indicate that though no granite outcrops within two miles it may exist at a 
coraparativeh' small depth. It is therefore possible that the supposed igneous rock has 
been wholly recrvstallized under the influence of the plutonic intrusions. 

(15.) From Vanina Stream (tributary of Doctor Creek). 

The specimen was taken from a point near the somewhat arbitrary boundary between 
the dark schists and the lower mica-schists. 

The hand-specimen is a dark, close-grained rock, with small white spots (feldspar). Schis- 
tosity is apparently quite moderate, and there is hardly any tendency to develop lamination. 



PLATE XX. 







Micrto-pnoTOGR.u'HS by Dr. P. M.\I{siiall, 

1. Feldspathic biotite-schist, Open Creek. Illustration shows feldspar eyes in a matrix of biotite, &c. 

2 Gneissoid rock, Headover Creek. Illustration shows feldspar, quartz, biotitic mica, &c. 

3. Quartz-feldspar-schist, Gorge Creek. 

4. Altered volcanic rock, near second gorge of Tuke River. 

All magnified about 25 diameters. 



f!eol. null. Xo. 6 ] 



I'To fare patje 9S. 



93 

Under the microscope, however, schistositv is seen to be very strongly developed, the 
finer material being arranged in bands, which ^v^ap round the larger grains. 

PVldspar, much epidotized and calcified, is the chief constituent, occurring as numerous 
subangular to rounded grains, which now show no twinning. A few broken grains of some 
ferro-magnesian mineral, now partly opaque from development of a brown, dusty substance, 
but still showing longitudinal cleavage, polarisation colours, and extinction at a consider- 
able angle to the cleavage,, may be seen. These, from their characters, probably represent 
augite. 

There is some rauscovite. and a little biotite in the section. 

Magnetite, in irregular grains and small cubes, with dull surfaces, may be original. 

Quartz is fairly plentiful in small veins and masses with mosaic structure. 

Epidote in small grains is scarce, but calcite is very abundant, and chlorite, probably 
replacing biotite, is noticeable as small ragged masses. 

The original igneous character of this rock can hardlv be doubted. 

(16.) From Vanina Stream. 

The specimen is taken near the point where the dark schists were seen to give place to 
mica-schists. 

The hand-specimen is a dark, tough rock, with highly contorted schistose structure in 
addition to fairly parallel foliation planes. It effervesces with cold dilute hydrochloric acid. 

Under the microscope it is seen to consist principally of biotite, quartz, and calcite, 
with a little feldspar, pyrite, magnetite, or other iron-o.xide, chlorite, and opaque strings of 
light-coloured material. 

The biotite is mostly in little, drawn-out patches follomng the highly curved lines of 
schistosity. 

Quartz is not in lamin;p, as in typical quartz-mica-schists, but in small grains, which 
probablv represent broken-up larger masses, and occurs also as secondary- grovvi;hs along 
the planes of schistositv. Manv of the quartz grains are silicified feldspars. In one or two 
of these silicification is not complete, and albite twinning is faintly \'isible. 

The presence of abundant calcite is noteworthy. Whether the lime is derived from 
the original constituents of the rock or from an outside source cannot be determined. 

(17.) From Vanina Stream, a little to the east of No. 16. 

• The hand-specimen is a dark schistose rock, much less contorted than No. 16. 

Under the microscope the section shows the following minerals: Biotite, cjuartz, tri- 
clinic feldspar, garnet, a little epidote, possible wollastonite, titanite, a very little calcite 
or other carbonate, and .strings of nearlv opaque material. A schi.stose structure is well 
developed. 

The biotite is in small, drawn-out patches, as in the rock last described. 

Quartz is abundant, mostly in small grains ; but there are also little veins. Some is 
.silicified feldspar. 

Well-twinned feldspar grains are not uncommon. Pericline as well as albite twinning 
may be seen. Judging by their general appearance and the angle of extinction, the feldspars 
approach oligoclase and andesine. 

Garnet is present as numerous small, well-rounded grains, often cracked. 

A colourless monoclinic (or triclinic) mineral present has many of the characters of wollas- 
tonite, but could not be certainly identified. 

Titanite appears in rather numerous grains, which show a tendency to elongated-lozenge 
shape. 

Remarks.— This rock, which is now a feldspar-quartz-biotite-schist. may originally have 
been an igneous rock. With it compare Nos. 15 and 16. 



94 

(2.) Mica-schists. 
(18.) From Dick Creek, ueai' Pouiiamu Formation (east side of Whitcombe River). 

'I'he hand-specimen is a light-coloured schist, consisting principally of qiiartz bands with 
dark specks of mica along the foliation -planes. 

Under the microscope, besides quartz and biotite, a little muscovite, triclinic feldspar, 
amphibole, titanite, magnetite, pyrite, and epidote are visible. The quartz does not show- 
strain extinction. Feldspar grains are very rare, but occur fresh and well-twinned in the 
quartz mosaic. 

(19.) From slopes of Mount Bowen, near Pounamu Formation. 

The hand-specimen is like No. 18, but its structure is far less schistose and biotite much 
more abundant. 

lender the microscope the section consists mainly of quartz and large flakes of biotite, 
arranged with little appearance of schistosity. Magnetite is present in numerous compact 
grains, and some of the biotite is a little chloritized. 

The quartz grains are crowded together, and in them are embedded numerous small 
prisnas of a colourless mineral, with rather low to moderately bright polarisation colours and 
oblique extinction, which resembles the substance in section No. 17 referred to possible 
wollastonite. 

(20.) From Mount Inframeta, near a serpentine outcrop. 

The hand-specimen is a grey schist, with many spangles of brown or yellow mica. 

Under the microscope the section shows characteristic schistose structure, and is seen to 
consist of biotite, muscovite, quartz, garnet, magnetite, and epidote. 

The biotite is partly in large scales and lens-shaped flakes, which form distinct eyes in 
the fine-grained groundmass. The cleavage is inclined at various angles to the lines of schis- 
tosity. The rest of the biotite forms long, narrow strips. The groundmass is made up of 
small grains and scales of quartz, muscovite, and biotite, with a little magnetite and epidote, 
and a few small garnets. 

(21.) From Mikonui Spur (between Dickson and Mikonui rivers). 

The hand-specimen is a highly contorted quartz-mica-schist. 

Under the microscope the schistose structure is well illustrated. The minerals present 
are quartz, biotite, a little muscovite, garnet, magnetite, possible hornblende, rutile, &c. 

The quartz is in irregular mosaics and bands. The extinction is generally normal, but 
is occasionally undulose. The individuals have sometimes been broken, rolled out, and re- 
crystallized. Not a few of the quartzes are suspiciously like silicified feldspars, and in two 
or three cases indubitable albite twinning may be seen. Whether these are really feldspars 
or silicified grains in which the original structure has been preserved during silicification 
is not ea?sy to determine, but the latter interpretation seems preferable. 

The biotite occurs in drawn-out masses and bands in the manner characteristic of typical 
mica-schists. 

The single garnet crystal present forms an eve in the schistose matrix. It is partly broken 
up along one edge. 

Rather doubtful hornblende occurs as occasional small prisms enclosed in mica, &c. ; 
there are also a few sagenitic needles in some of the biotite patches. 

{.3.) Grawracles. 
(22.) From valley of Upper Mungo. 

The hand-specimen is a tough, grey, rather coarse-grained indurated grauwacke. 

Under the microscope it is seen to consist of fragments of quartz, feldspar, biotite, and 
magnetite, with some epidote, uncertain green material, and some kaolinitic or dark material. 



96 



Quartz grains of fairly uniform size form the greater part of the minerals present. Many 
of the grains are possible silicified feldspars. 

The feldspars are generally finely twinned, and all appear to l)e of acid types. Most are 
tresh, though some are epidotized. 

Biotite occurs in small Hakes, apparently all original. .Magnetite is also an original 
constituent. 

(23.) From valley of Louper Stream, half a mile south of Whitcorabe Pass (on the Canterbury 
side.) 

The hand-specimen is a typical fine-grained, rather Ught-coloured grauwacke. 

L'nder the microscope it has the same general appearance as No. 22, but twinned 
feldspar is absent. It is more altered, and any original feldspar has been epidotized or 
silicified. 

AncUysea. 

The following ten analyses of material from the alpine area represent the bulk of the 
rocks included in the Arahura Series : — 



— 


1. 


2. 


3. 


4. 


5. 


t). 


7. 


n. 


9. 


10. 


Silica (SiOo) 


6809 


70-18 


71-93 


69-97 


62-16 


56-73 


72-32 


7018 


63-40 


68-20 


.\lumina (.Al^^Oa) 


14-34 


14-15 


13-39 


1502 


14-73 


17-33 


16-40 


16-26 


16-03 


16-63 


Ferric oxide (Fe.U,) 


016 


0-28 


0-12 


0-56 




0-80 


0-24 


0-46 


0-68 


004 


Ferrous o.xide (FeO) 


4-39 


3-53 


3-31 


.5-(12 


fi-41 


(r40 


0-48 


2-84 


712 


314 


.Manganou.s oxide (MiiO). . 


0-26 


0-32 


0-3C 


()-35 


0-40 


0-35 




0-27 


010 


0-30 


Lime (CaO) 


1-48 


1-21 


2-45 


3-73 


3-23 


3-60 


2 05 


2-87 


2-50 


2-46 


•Magnesia (.MgO) 


1-57 


101 


0-91 


3-26 


2-87 


500 


0-50 


2-58 


3 07 


1-30 


Pota-sh (K.,0) .. 


3-23 


2-48 


2-20 


2-47 


3-30 


0-85 


4-64 


0-78 


217 


2-33 


Soda (N'a.,0) .. 


2-90 


4-95 


409 


2-55 


2-52 


3-37 


2-45 


0-43 


2-69 


2-43 


Phosphoric anhydride (PjO^) 


0-28 


017 


0-18 


0-37 




0-21 


019 


0-32 


0-22 


0-23 


Sulphuric antivdride (SO.,) 












Oo9 


017 






0-13 


Titaaiuin-oxide (TiO.,) .. 


0-66 


0-46 


0-49 


0-95 


0-61 


0-86 


001 


0-70 


1.08 


0-31 


Carbonic anhydride (CO 2) 




0-60 




3-22 


2-40 


0-20 


05 


0-08 


05 


005 


Organic matter and combined water 1 
Moisture (at lOO^C.) .. .. , 


209 


109 


0-80 


1-83J 


0-85 


■2-63 
,0-92 


0-72 
015 


1-47 
0-37 


104 
015 


1-75 
0-55 




99-45 


100-43 


100-23 


99-90 


99-48 


99-84 


100-37 


99-61 


100-30 


99-84 



1. Quartz-mica-schist from Mount .lumbletop. 

2. Quartz-mica-schist from Toaroha Canyon. 

3. Mica-quartz-schist from (irimmond Creek, Mikonui River. 

4. Schistose rock from second gorge of Tuke River. Petrologically described as No. 11. 

5. Probal)le igneous rock from second gorge of Tuke River. Petrologically described 
as No. 12. 

6. Dark subschistose rock near Hende's, Wanganui River, probably of igneous origin. 

7. Light-coloured gneissic schist, Hugh Creek. Mount Bonar. Contains muscovite. 

8. Schi.stose rock from Open Creek, Mikonui River. Petrologically described as No. 5. 

9. Coarse-grained schistose rock from Headover Creek, Mikonui River. Petrologically 
described as No. 6. 

10. Grauwacke from Mungo River. Petrologically described as No. 22. 



96 



^CHAPTER VII. 



THE GREENLAND SERIES. 



Page ( Paa» 

Age and Correlation . . . . . . 96 General Petrology . . . . . . 97 

Distribution .. ..96 (1.) Grauwackea .. .. ..98 

Structure .. .. .. ..97 (2.) Argillites .. .. ..98 

Relation of Structure of Series to that Special Petrology . . . . . . 99 

of the Southern Alps . . . . 97 Analyses . . . . . . . . 101 

Age and Correlation. 

The rocks described in this chapter under the name of the Greenland Series are equivalent 
to the Kanieri Series of the Hokitika Bulletin ; but, since the name " Kanieri Series " has been 
used by Cox and McKay as equivalent to the Blue Bottom and associated beds, it has been 
deemed advisable to adopt another name — that of the well-kno\\Ti moimtain near Ross, in 
which the beds in question have a very full development. The Greenland beds were examined 
by Cox in 1875. and by him classed with the auriferous rocks of supposed Carboniferous age 
occurring at Reefton, which he believed to belong to the Maitai Series.* McKay has con- 
firmed Cox's correlation :t but, since this correlation is based entirely on lithological features, 
it seems desirable that an alternative locality name should be pro\-ided for the series as 
developed in the Mikonui Subdi"\nsion. The rocks of the Greenland Series have been further 
correlated by both Cox and McKay with the non-schistose rocks occiirring near the main divide, 
and described in the last chapter as forming the uppermost members of the Arahura Series. 
There is a strong lithological resemblance between the last-named beds and the Greenland 
rocks, and probably both have been derived from the waste of the same ancient land- area. 
Again, both are more or less auriferous, though there are noticeable differences in the 
character and number of quartz lodes. While, however, the lithological resemblances and the 
mode of occurrence justify the pro\-isional acceptance of the correlation, final judgment"must 
be suspended until further proofs are forthcoming. Two points that" will require explanation 
are the absence of fossil annelids from the Greenland Series and the absence from the Upper 
Arahura of the thick band of greenish argillites well seen on the south-western slopes of Mount 
Greenland. 

Distribution. 

The Greenland Series extends over an area practically coincident with that occupied by 
the outer hills described in Chapter IV. From this area must be excluded certain granite bosses, 
and small patches which are occupied by beds of Koiterangi and younger Tertiary age, though 
underlain bv rocks belonging to the series. Part of Koiterangi Hill and an isolated area east 
of Doctor Hill are occupied bv Greenland beds. West of Doctor Hill the series covers a large 
extent of countrv reaching as far as the Mikonui, and taking in the northern slope of Moimt 
Rangitoto, on the west side of that river. There are two small apparently isolated patches 
in the Upper Mikonui Yallev, one north-west of Gribben's Homestead, the other across the 
river on the west side, but these are really part of the large area just indicated. On the south 
slope of Mount Rangitoto nearly three square miles is covered by a mass of Greenland grau- 
wackes surrounded on all sides, and no doubt underlain, by granite. Some miles to the south- 
west a small isolated outcrop forms the Waitaha Sugarloaf. 



* " Report on Westland District," G.S. Rep. during 1-874-6, vol. ix,''1877, p. 76. 

t "Geological Explorations of the Northern Part of Westland," Mines Report, 1893, C.-3, p. 171. 



PLATE XXI. 




l{AX(;noTo 1{\x(;k ihom Haity Vai.i.ky (Kakapotahi 1\ivbk). Mount Uancitoto (:J,()i)r) ft.) is 

ABOUT CENTRE OK VIEW. 




\'iE\v IHOM IIati'v Vai.i.ey towards Sources of Kakai'otahi Kivek. Part of Moui^t Alle^j 

ON RIGHT. 



Geol. Dull. So. 6'.] 



[Tu jace -pcujc 96. 



97 

The extreme length of the district over which the Greenland Series is found is between 
seventeen and eighteen miles, and the greatest width about eight miles. The area over which 
It actually outcrops or is covered by a small depth of modern gravels is approximately fifty- 
five square miles. 

South of the Waitaha Sugarloaf the Greenland Series is not agam seen in the subdivision, 
but It reappears many miles outside its boundaries near Lake Mapourika.* 

Structukk. 

The rocks of the Greenland Series are thrown into a number of well-developed 
folds. The strike direction, a few exceptional cases omitted, varies from somewhat west 
of north (3-48°) to north of west (280°), and is ordinarily within a few degrees of a bearing 
of 300°. The dip is usually about 60° to 70°, but may be as low as 30°, and sometimes 
reaches 90°. 

Except that they are somewhat disturbed by the granite intrusions, and considerably 
affected by faulting in certain areas, the folds, c-ompared with those of the Arahura, are 
wonderfully regular and free from complication. In the section from the Kakapotahi River 
to Koiterangi Hill there are three anticlines and two synclines. The granite bosses of Mount 
Rangitoto and of Doctor Hill break through two of the anticlines. With the exception of 
Mount Rangitoto. where thermal metamorphism by indurating the grauwackes has aided 
in their preservation, the highest parts* of the area in which the Greenland Series occurs 
have a synclinal structure. The main structural features are clearly illustrate^ in 
the geological section from the Waitaha Vallev to Koiterangi Hill, which accompanies this 
report. 

Relation of Structure of Series to that of the Southern Alps. 

It has already been pointed out that the folding of the Greenland Series in a direction 
almost at right angles to the prevailing trend of the Southern Alps is one of great interest, 
but the fact is of such importance that a further reference to its significance will be willingly 
pardoned. 

The Greenland Series is nowhere found in actual contact with the Arahura Series. The 
nearest outcrops that could be discovered are separated by distances of nearly a quarter of a 
mile, and along the line where the two series should junction we find either granite or a cover 
of modern gravels occupying river-flats, stream-valleys, &c. 

The phenomena observed indicate not an unconformity, but a great fault, which can 
hardly be other than a reversed fault or overthrust. Tp the inclined plane of this fault the 
rocks composing the Southern Alps have been thrust in comparatively recent times until 
the impelling force.s were spent. Further, the comparatively gentle and regular folding of 
the Greenland rocks, as well as its direction, indicates that so far as exposed in the area they 
have never been involved in either the Alps or the approximately parallel ranges, which 
are believed to have existed to the west in Early Tertiary and possibly as far back as the 
Pala'ozoic periods. Some sign, however, of an old disturbing influence is apparent near 
Ross, but it is difficult to dissociate it from the disturbance due to comparai/ively modern 
faulting. It is (|uite possible that the corresponding rocks in the Hokitika Subdivision near 
Lake Kanieri have been somewhat involved in the orogenic movements which have produced 
the Alps. 

General Petrology. 
The Greenland Series consists practically of only two kinds of rock — (1) grauwackes 
and (2) argillites. 



S. H. Cox: " Report on Westlan.l District.'" G.S. Rep. during 1874-6. vol. ix, 1877, p. 77. 
7 — MikoQui. 



98 

Generally speaking, the grauwackes form the lower beds, but fine-grained bands are 
often interbedded with them, especially as the higher beds are approached, where the argillites 
have a considerable development. The finer-grained beds appear well adapted for the pre- 
servation of fossils, but none have ever been found. It must therefore be concluded that the 
Greenland Series was laid down under conditions which were unfavourable to animal or 
vegetable life. 

As a whole, the Greenland beds appear to be very shghtly, if at all, affected by regional 
metamorphism. Near the granite bosses the effects of thermal metamorphism, while well 
marked, are moderate in degree, and do not always extend as far from the actual contact with 
the plutonic rocks as might be expected. 

(1.) Grauwackes. 

Macroscopically the grauwackes are compact, tough rocks of dark-grey or bluish-grey 
colour. They are often coarse in grain and very harsh to the touch. Jointing is fairly well 
developed as a rule, and when the bands of grauwacke are of uniform grain it is difficult to 
distinguish the bedding-planes. 

Schistosity is almost absent, except where fault-movement has given rise to it in a shght 
degree. In places, especially near Eoss, the grauwackes are shattered to an enormous ex- 
tent along great fault zones, but even liere schistosity is not greatly developed. Near the 
granite contacts the grauwackes become exceedingly tough and close-jointed. Biotite appears 
in increasing quantity, and gives rather a peculiar sheen to hand-specimens. This sheen 
becomes noticeable a quarter of a mile or more from the contacts, and is sometimes apparent 
at even greater distances. In the latter cases, however, it is generally tolerably certain that 
granite imderlies the micaceous rock at no great depth. 

Under the microscope the grauwackes ordinarily consist mainly of angular fragments 
of quartz and various feldspars. Biotite is always present, and though much is secondary, 
some may be original. Epidote generally forms a considerable part of the groundmass, invading 
the feldspars, and even penetrating cracks in the quartz grains. Some calcite is usually 
present. 

In fthe lease of the Koiterangi Hill grauwackes and other specimens showing the 
biotite sheen, metamorphism has advanced to such a stage that little or no feldspar is 
recognisable under the microscope. The sections show a mosaic of quartz and biotite, 
\vith a few flakes of muscoA-ite. A little magnetite is present, but there is no epidote or 
calcite. 

Although the biotite in these altered grauwackes is arranged along planes parallel to 
the bedding, it is more or less interlocked with the quartz, and the schistosity that results is 
slight. There is but a moderate tendencv to split along these planes, and there is no real 
development of foliation or lamination, such as is seen in the true mica-schists of the alpine 
range. 

(2.) Argillites. 

The argillites are most extensively developed on the slopes of Mount Greenland, 
where they are interbedded with the upper layers of the grauwackes. One band, several 
hundred feet in thickness, is well seen along the foot-track leading from the summit of 
the mountain to the Cedar Creek horse-track, near Veronica. Argillite bands of less 
thickness are also seen on the summit of Constitution Hill, and in Farmer, Weir, and 
Humbug creeks. 

Megascopically the argillites are fine-grained rocks, often of a greenish-grey colour, some- 
times dark-grey, in which cleavage parallel to the bedding-planes is usually well developed, 
so that the rock resembles a true slate. In Humbug Creek a band of dark-grey material 



99 

was seen, which, besides the ordinary bedding-cleavage, exhibited a weU-marked cleavage, 
crossing the bedding-planes at an acute angle. 

Under the microscope the argillites appear to be much altered, and show a fine-gramed 
mosaic, consisting principally of amphibole, possible serpentijious material, and biotite. In 
the coarser bands, which approach grauwacke, quartz grains are plentiful, and a few fragments of 
feldspar may be seen. 

Special Petrology. 
Under this heading a few typical rock-sections will be described. 
(1.) From Cedar Creek (Veronica) Track, Mount Greenland. 

The hand-specimen is a fine-grained well-banded rock of a greenish-grey colour, typically 
representative of the Mount Greenland argillites. 

Under the microscope the section exhibits a fine-grained mosaic and a comparatively 
coarse band. 

The fine-grained mosaic with a fairly high power seems to consist of an amphiboHc mineral, 
a colourless mineral with very moderate to feeble polarisation colours, and some biotite. It 
has a distinctly banded structure, well seen when the nicols are crossed. 

The amphibole is in light-yellow laths, resembling those which often form in altering 
feldspars. It has slight pleochroism, fair double refraction, and a maximum extinction-angle 
of about 18°-20°. 

The colourless mineral has some of the characters of serpentine, to which it may very 
doubtfully be refeiTed. but the analysis (No. 3) at the end of this section suggests some 
aluminous mineral. 

The coarser band consists of fragments of quartz, with a few feldspars (some polysyn- 
thctically twinned), biotite, a little chlorite, and patches of the amphibolic and serpentinous 
minerals described above. 

A little iron-ore in the form of dark grains is scattered through the section. 

Remarks. — The original minerals of the fine-grained mosaic of the specimen appear to 
be completely obliterated. Epidote is not present, and the greenish colour is possibly due 
to serpentinous material. 

(2.) From Donnelly Creek, near Ross. 

Megascopically the specimen appears a liard, medium-grained grauwacke. It effervesces 
slightly with cold dilute hydrochloric acid. 

Under the microscope the section is seen to consist of quartz, feldspar, biotite, magnetite, 
epidote. calcite, and pyrite. The grains var^' considerably in size, but, on the whole, are 
rather small. 

Quartz is in rounded and subangular grains, which extinguish uniformly. A little 
secondary quartz may be present. Some of the feldspar is completely altered to a 
mosaic, consisting principally of epidote and calcite ; whilst other grains are rather 
fresh, and exhibit polysynthetic twiiming. Some, from the angle of extinction, may be 
oligoclase. 

There is some original biotite. one individual of which shows a bleached non-pleochroic core, 
together with many small patches of secondary biotite. 

Magnetite is in small grains, apparently all original. 

Epidote and calcite are present mainly as alteration-products of the feldspars. 

The only other mineral calling for mention is pyrite. of which a nest occurs in one part 
of the section. 

7' — Mikonui. 



100 

(3.) From Flat Creek, Mount Rangitoto. 

The hand-specimen is a fine-grained, tough indurated rock, witli general hut rather taint 
micaceous glimmer, and is of a light-grey colour. 

Under the microscope it consists almost entirely of quartz and biotite. with a little 
magnetite, &c. 

The fjuartz is in grains, many with an outline which might perhaps best be described 
as irregularly crenulate. Some, as is indicated by the included dust, appear to replace 
feldspar. Most of these grains under crossed nicols are seen to consist of two or more 
individuals. In at least two instances the separating-line is straight, suggesting a Carls- 
bad twin. 

Biotite is in small flakes, which wrap round and sometimes penetrate the (|uartz grains. 

An analysis of the rock is given at the end of this section. 

(4) and (5.) From Koiterangi Hill. 

The hand-specimens are close-grained grey rocks, with micaceous sheen. 

Under the microscope the sections have the characters of much altered grauwackes, and 
exhibit a mosaic consisting principally of quartz and biotite, with a little magnetite. 

The quartz is in small grains, which under a high power are seen to be corroded at the 
edges, and gi\ing place to secondary quartz grains and biotite. 

Biotite is in irregular plates and small laths, some of which are onlv moderately 
pleochroic. 

(6.) From Waitaha Sugarloaf (east side), Waitaha Valley. 

The hand-specimen is a dark micaceous rock, apparently a much altered grauwacke. 

Under the microscope the section resembles Nos. 4 and 5 in being composed almost 
entirely of quartz and biotite. with a few small grains of other minerals. 

The quartz is in somewhat interlocking grains of various sizes, some of which appear to 
nave replaced feldspar. The extinction is regular, not showing any strain phenomena. 

Biotite forms numerous j;ood-sized laths and plates. The laths are often seen penetrating 
the quartz grains, and in some cases passing through them. 

This peculiarity, taken in conjunction with other appearances, leads one to think that 
most of the quartz must belong to a secondary crystallization. 

Remarks. — The rock is probably a grauwacke of the Greenland Series, much altered bv 
thermal metamorphism induced by underlying granite. An analysis is appended at the end 
of this section. 

(7.) From granite-grauwacke contact, Humbug Creek. 

The hand-specimen is a grey indurated rock, with marked micaceous sheen. 

Under the microscope the section is seen to consist of (|uartz, biotite. muscovite. feldspar, 
and a little magnetite. 

The greater part of the quartz is in large irregular masses which are in nearlv complete 
optical continuity, and enclose numerous small laths of biotite, muscovite, &c. Some is 
in smaller grains, a few of which mav represent silicified feldspars, and there is a quartz vein on 
one side of the section. 

Biotite is verv plentiful in small laths, whilst muscovite appears in nmch smaller 
amount. 

Feldspar occurs to a limited extent as small irregular plates which sliow poor twinning, and 
opear to be partly silicified. 



101 



Analyses 



•Silica (SiOj) 

Alumina (AljO,) 

Ferric oxide (FcjOj) 

Ferrous oxide (FeO) 

Manganous oxide (MnO) 

Lime (CaO) 

Magnesia (MgO) 

Potash (K^O) 

Soda (XajO) 

Phosphoric anhydride (PjO.) 

Sulphuric anhydride (SO3) 

Titanium-oxide (Ti^O) 

Carbonic anhydride (COj) 

Organic matter and combined water 

Moisture (at 100° C.) 



1. 


2. 


3. 


70-81 


71-80 


55-80 


12-53 


12-54 


2179 




0-48 


10* 


518 


4-12 


6-26 


0-62 


0-25 


0-20 


1-96 


3-51 


0-25 


2-84 


2-28 


4-57 


4-31 


2-27 


4-96 


010 


1-17 


115 


* 


0-18 


015 


* 


0-28 


0-10 


0-58 


0-60 


0-89 


010 


0-05 




- 0-77 


jO-55 


2-91 




10-25 


0-25 










99-80 



100-33 



1. Micaceous grauwacke from Flat Creek, Mount Rangitoto. 

2. Micaceous grauwacke (highly alt«red) from Waitaha Sugarloaf. 

3. Argillite from Cedar Creek Track. 



100-32 



• Not determined. 



102 



CHAPTER VIII. 



THE KOITERANGI SERIES. 





Paae 




Content and Conditions of Deposition . 


. 102 


Palaeontology 


Age and Correlation . . ... 


. 102 


General Petrology 


Distribution 


. 103 


Special Petrology 


Structure .. 


. 103 





Passe 
104 
104 
105 



Content and Conditions of Deposition. 

The rocks classified as belonging to the Koiterangi Series consist of a basal conglomerate 
of great thickness, followed by grits, sandstones, and limestones. The lower layers of the 
conglomerate are of glacial origin ; the upper layers are fiuviatile, and grade into coarse grits. 
The grits are followed by sandstones containing small impure seams of coal, and plant-remains 
which are poorly preserved. The upper sandstone layers, which are more or less calcareous 
and may be considered as littoral deposits, are succeeded by purely marine fossiliferous hme- 
stones of considerable thickness. The limestones contain broken shells, fucoid casts, and 
Foraminifera ; but unfortunately the fossils, wath the exception of the Foraminifera. are not well 
preserved. If closely studied, however, they may possibly afford valuable data concerning 
the age of the series. 

It is evident that the later beds at least of the Koiterangi Series were laid down during 
a period of land-depression, which in this report is considered to have correspondedy,with 
the Oligocene period. At first there was high land in the neighbourhood of the Mikonui Sub- 
division, possibly to the west, from which glaciers descended into the lowlands. Later the 
glaciers retreated, but rivers continued to bring down coarse gravels from the mountains. 
Depression must have gone on at a greater rate than deposition, for the coarse gravels gave 
place to grits, and then to shales with coal-seams, which were soon followed by the marine 
sandstones and limestones. Deposits corresponding to the upper beds of the Koiterangi 
Series may once have extended over much of the South Island, and not improbably over the 
greater part of the area now occupied by the Southern Alps. 

Age AiTD Correlation, 

The Koiterangi Series may safely be correlated with the coal-measures of the Grey and 
BuUer districts, which were placed by Sir James Hector in the Cretaceo-1'ertiary or Coal 
Formation of New Zealand. Captain Hutton considered the Grey coal-measures to be of 
Amuri (Cretaceous) age, but the overlying Cobden limestone he, in common TOth Von Haast, 
thought to be separated by an unconformity from the coal-bearing rocks, and to be of 
Oligocene age.* There seems to be no clear evidence of unconformity at Greymouth, and 
there certainly is no sign of unconformity at Koiterangi. There may, however, be a strati- 
graphical break at a higher horizon than the Koiterangi limestone in the Cobden limestone. 

In 1903 Professor Park was of opinion that the Grey and BuUer coal-measures belonged 
to the Waipara Formation, of Cretaceous age.f 

On the whole, then, the weight of the various authorities quoted is in favour of ascribing 
a late Cretaceous age to the West Coast coal-measures ; nevertheless, it is admitted that the 

* " On Some Fossils lately obtained from the Cobden Limestone at Greymouth," Trans. N.Z. Inst., vol. xx, 
1887, p. 268. 

t " On the Age and Relations of the New Zealand Coalfields," Trans. N.Z. Inst., VoL xxxvi, 1903, p. 418. 



103 

marine fauna is almost entirely Tertiary, and therefore, until an unconformity is proved 
between the manne beds and the coal-bearing strata, it would appear that a Tertiary rather 
than a Cretaceous age ought to be assumed. In this conflict of evidence it is manifestly 
mipossible to state the age of the Koiterangi Series with certainty or exactness. Possibly 
the lower beds are of Eocene age, whilst the upper part of the series is of Oligocene age or 
if the Oligocene be discarded from the table of New Zealand formations, of Lower xMiocene 
age. 

Distribution. 

Both within and u-ithout the subdivision the original coal-measures have been much 
reduced in extent during the great period of denudation which began towards the close of 
Miocene times, and still continues. Various areas have been faulted to unknown depths and 
covered by later deposits, so that there are no\\ exposed quite minor patches of a formation 
which once probably covered much of the subdivision. 

The most important of these remnants is at Koiterangi Hill, the greater part of which 
consists of the typically developed beds of the series. Somewhat over one-half of the hill is in 
the Hokitika Subdivision and was described in the bulletin referring to that area.* A very 
small hillock of conglomerate, evidently connected below the superficial gravels with the Koi- 
terangi area, outcrops on the Koiterangi-Kokatahi Plain two miles east-south-east of Koi- 
terangi Trigonometrical Station, and about a mile from the foot of the hill itself. Some six or 
seven miles south-west of Koiterangi Hill fault-involved beds of conglomerate and sand- 
stone belonging to the series appear near the head of Humbug Creek and on Ford Ridge, 
just outside the western boundary-line of the Arahura Series. If this line be followed to the 
north-east it passes near a spot east of Doctor Hill, where coal is said to have been discovered 
many years ago. Careful search was made in this neighbourhood for coal, but without success. 
Probably, however, a very small area of coal-measure rocks does exist in this locality. 

To the south-west of the Humbug Creek area there are several small outcrops of Tertiary 
rocks which may possibly belong to the Koiterangi Series, but have been referred to the 
overlymg Upper Miocene beds. 

The patch of limestone at the head of Hodson Creek, near Ross, occupying at most only 
a few acres, is thought by the writer to be the equivalent of the Koiterangi limestone, but may 
with almost equal likelihood be considered as the lowest of the Upper Miocene beds. 

Structure. 

The Koiterangi Series rests with a high degree of unconformity upon the grauwackes of 
the Greenland Series, and is evidently not involved in its north-west to south-east folding. The 
field evidence shows that besides being traversed by minor faults, especially at Koiterangi, 
the areas in which the series occur are bounded wholly or partly by notable faults, as a result 
of which the beds are considerably tilted. At Koiterangi Hill and Humbug Creek the general 
strike is from east of north to west of south, and the dip from 10° to 25° in a direction south 
of east, though as a result of minor faulting the dip and strike in the former area vary con- 
siderably. The limestone at the head of Hodson Creek has probably the same strike and 
dip directions as the beds of the other areas, but the dip is much steeper, probably quite 80°. 

The Koiterangi Series shared in the last main uplift of the land, as is shown by the 
marine beds appearing at elevations of 1,841 ft. in Koiterangi Hill and over 2,000 ft. near 
the head of Humbug Creek. The various exposures lie to the west of the main mountain- 
range, and therefore have not been involved in its folding, though in its last stage that may 
be of post- Koiterangi age. Not improbably, however, at Humbug Creek, and perhaps 
elsewhere, the rocks of the Arahura Series have been pushed over areas of Koiterangi rocks 
for a short distance ; but there is no direct evidence of this having happened. 



• BulL No. 1 (New Series), N.Z.G.S., 1906, pp. 78-80. 



104 

PALiEONTOLOGY. 

The Koiterangi conglomerates, as might be expected, contain no fossils of any kind, but 
the grits and lowe? sandstones, besides coal, contain numerous scattered plant -remains. These 
usually take the form of broken pieces of carbonised wood and small plants (? reeds), all quite 
unidentifiable. It is probable that caref\il search, especially in the Humbug Creek area, 
where the beds tend to become shaly, might discover recognisable leaf-impressions, but such 
were not found during the course of the present survey. 

The Koiterangi limestone exhibits fucoid casts : numerous Foraminifera of several genera, 
well seen in microscopic sections ; together with a few molluscan shells, which are nearly 
alwavs broken or poorlv preserved, and are invariably so embedded in the hard, lough lime- 
stone as to be inextricable in any ordinary way. The most common species is a rather flat 
bivalve of oval outline, apparently about liin. to 2 in. long. The Foraminifera include 
Glohigerina conglomerata{l), Lagena, Textularia or similar genus, Rotalia, CristeUaria(^, and 
other genera. 

In the Humbug (reek area the marine fossils appearing in the upper calcareous sand- 
stone consist mainly of a species of Ostrea, perhaps the '" black oyster " of the Waipara Series : 
but the shells are oulv partly preserved, the outer portions having disappeared, and are, more- 
over, so distorted that specific identification cannot be attempted. Calcareous boulders full 
of beautifully preserved specimens of a Turritella species were found in the creek, and may 
have come from Koiterangi beds. 

The limestone at the head of Hodson Creek shows numerous Foraminifera of several 
genera, together with fragments of various shells, and possibly of sponges, Bryozoa, &c. 

Gkxer.\l Petrology. 

The rocks of the Koiterangi Series will be described under the headings of — (1) Con- 
glomerates, (2) grits and sandstones with coal-seams, and (3) Umestones. 

(1.) Conglomerates. — These have a great development on Koiterangi Hill, where they attain 
a thickness of over 1,000 ft. The pebbles here consist mainly of grauwacke, together \vith 
a little slate and numerous pieces of broken quartz. The absence of mica-schist, granite, 
and serpent ne is a most interesting and important fact, the significance of which was pointed 
out on page 3-1. The material in which the larger constituents are embedded consists of 
a more or less indurated paste of arenaceous and argillaceous matt«r, containing much oxide 
of iron (FejOg), which gives a characteristic red colour to the greater part of the conglomerates. 
The lower beds of the conglomerate as seen at Koiterangi contain numerous large angular 
or subangular boulders, and are almost certainly of glacial origin, a conclusion which is con- 
firmed by ob.servations made in other districts, for the existence of glacial debris at the base 
of the New Zealand coal-measures has been suspected both by Von Haast and McKay. The 
former writes that coarse breccia beds which appear to be derived from raorainic accumula- 
tions are found along the banks of the Grey River,* whilst McKay records similar beds from 
the Inangahua Valley.! 

The pebbles of the upper beds of the conglomerates are of medium size, and loimded, 
thus evidencing a fluvdatile origin. At Koiterangi they gradual!}' become finer, until at last 
they paSvS into the beds of the next division. At Hiuubug Creek the conglomerate consists 
of large rounded pebbles of decomposed grauwacke, and a little quartz, embedded in a firm 
matrix of red colour similar to that seen at Koiterangi. These conglomerates are somewhat 
sheared owing to fault-movements, and where exposed they are considerably affected bj' 
weathering, which has removed more or less of the cementing matrix. There are occasional 
finer bands, which enable the strike and dip to be observed. As at Koiterangi, the con- 



* " Geology of Canterbury and Westland," 1879, p. 299. 

t " On the Geology of the Reefton District, Inangahua County," G.S. Rep., during 1882, voL xv, 
1883, pp. 142-144. 



PLATE XXII. 




I'.MiT 1)1' DOC'TOU llll.h AND Pk.KON lIlM, KliOM X EUniliOUHllUOl) UF IloKll IKA GoUGE 

Note iipi>arciit fault-scarp on right siilc <>f Pigcoi: Hill. 



^■^ 




;'-•■ -~- ^ ,.'V 



^ 



Korri:i{AN(;i Hii.i. Ki{0>r NEi(;HnouiiHOOi) ok Hokhika Cuin.i. 
Xotf probable fault-scarp on left of hill. 



Geol. null. \o. 0.] 






[To face pafjt 101). 



106 

glomerates gradually becomp finer as they are traced upwards. The lowest lavers are faulted 
below the surface, and are therefore not seen. 

(2.) Grits, Sandstonea. and Shales. — These are well developed both at Koiterangi and at 
Humbug Creek. On Koiterangi Hill, about a quarter of a mile south-west of the trig, station, 
good exposures are seen in a small creek-bed. The section shows about 130 ft. of grit and 
coarse sandstone overlying the fine conglomerates. .\n impure coal-seam 6 ft. to 8 ft. 
thick follows, 70 ft. above which is a carbonaceous shaly band of uncertain extent. Above 
this is a considerable development of bro\\ni grit and sandstone, probably 200 ft. or more. 
The total thickness of grits, sandstones, shales, &c., is therefore not less than 400 ft. Some 
bands of the sandstone are almost pure white, and of loose texture : but the uppermost layers 
are harder, owing to the presence of calcareous matter. 

Xt Humbug Creek the section is somewhat similar, but no coal-seam is visible, the grits 
exhibit marine fossils in the lowest horizon, and shaly bands are better developed. The 
shales here contain large numbers of pyritic concretions, nearly all of globular shape, with 
diameters ranging from .1 in. to about 2 in. They resemble the pyritic nuts reported from 
Mangonui. and their vegetable origin is apparently confirmed by the circimistance that some 
appear to contain carbonaceous matter. On the other hand, their varying size, and to some 
extent shape, are evidences against their being fossils. 

Limestones. — At Koiterangi Hill limestone covers an area of some hundreds of acres, 
more than half of which is within the subdivivsion. The thickness is about 250 ft. At the 
trig, station (1,841 ft.) it is white and somewhat soft, whilst at the lime-kiln (just outside 
the subdivision) it is a liard, tough, bluish rock of finely crystalline texture. On the south-east 
side of the liill it outcrops for some distance, and is here lighter coloured than at the lime- 
kihi. In the former locality th- limestone contains a high percentage of carbonate of lime, 
but ill other parts of the liill it is rather siliceous, and at times passes into a calcareous sand- 
stone. Glauconitic grains are conunonly present. 

At Humbug Creek no liniestoiu' is present, a fact which seems to indicate that shallow 
water or littoral conditions prevailed in this locality during the deposition of the Koiterangi 
limestone. The latter rock has been considerably denuded, but its small thickness when com- 
pared with the calcareous beds thirty miles to the noith near Oreymouth, which have a 
vertical range of 1,000 ft. or more.* suggests that it also was deposited near the old shore- 
line. 

The onlv other outcrop of limestone in the Mikonui Subdivision is that at the head of 
Hodson Creek. It is largely recrvstallized, but under the n^icroscope, as previously stated, 
shows numerous Foraniinifera and traces of other organisms. From an analysis it appears to 
be of good quality, but unfortunately the outcrop covers a verv limited area. 

Special Petrology. 
1. Limestone from near lime-kiln, Koiterajigi (just outside the subdivision). 

The hand -specimen is a blue, ver}' tough, fine-grained rock, with iiregular fi-acture. 

The microscopic examination shows the rock to cojisist mainly of caUdte, with numerous 
small, more or less rounded grains of quartz, some fresh well-twinned fragments of feldspar, and 
a little cloudy brown matter. 

A few small grains of pyrite are present, and there are one or two little patches of 
siliceous mosaic partly replaced by calcite, which may represent fragments of sponges or other 
siliceous organisms. 

The calcite is formed principally of the well-preserved remains of Foraminifera of several 
genera, the most abundant being Globigerina. with a few small shell-fragments. There has been 
very little recrystallization of the calcite. so that its organic origin is evident. 

♦ Von Haast (" Geology of Canterbury and Westland," 1879, p. 299) e^imates the thickness of the 
whole coal- bearing formation near Greymouth as at least 5,000 feet. 



106^ 

2. Limestone from head of Hodson Creek, near Ross. 

The hand-specimen is a nearly white, close-grained, but evidently recrystallized rock. 

The section consists almost entirely of calcite, vsdth one or two small^grains of quartz, 
a feldspar or two, and some cloudy matter. About half of the calcite is in the form of secondary 
crystals, which show fine twinning. 

The remainder is formed in great measure of Foraminiferal tests, consisting mainly of 
Globigerina, with Lagena and probably other genera. There are also certain fragments which 
show fairly well-preserved structures, probably recognisable by an expert. These remains are 
of more than one kind, some probably being those of Brachiopoda and Mollusca, whilst others 
are possibh^ calcified sponges or similar organisms. 

The feldspars are more or less calcified, some crystals especially so. 

Note. — For further information concerning the Koiterangi Series, see Bull. No. 1 (New Series). 
N.Z.G.S., 1906, pp. 78-81. Analyses of the coal and limestone of the series are given in Chapter xiv of thi» 
bulletin. 



107 



CHAPTER IX. 



UPPEK MIOCENE BEDS. 



Content and Conditions of Deposition . . 107 Paljeontology „ 1(^ 

Age and Correlation . , . . . . 107 General Characters .*" '* * " 109 

Distribution .. .. ..107 I Special Petrology .. .. no 

Structure . . . , . . . , log J 

Content and Conditions op Deposition. 
The beds classed as Upper Miocene in this bulletin occur in a number of isolated patches in the 
Totara Sui-vt-y District, and consist of calcareous niudstonos, grauwackes, conglomerates, 
grits, sandstones, and clays. It is possible that the Hodson Creek limestone, which has been 
included in the Koiterangi Series, also belongs here. The Upper Miocene strata are essentially 
littoral or shallow-water deposits, wluch were laid doMTi during a period when the level of the 
land was oscillating. To the east the Southern Alps were now rising, whilst the land to the 
west was sinking. Probably between the Alps and the western land ran a sheltered arm of 
the sea which opened to the north, but southward may have ended in the neighbourhood of 
Mount Rangitoto, which was then only a tew hundred feet above sea-level. Mount Green- 
land was either covered by the sea, or formed a narrow ridge between two arms 'of the 
ancient sound. On the present seaward side of Rangitoto the sound may have extended 
further southwai'd : its width must remain uncertaiii, but it certainly reached northward to 
the neighbourhood of Greymouth, and in it were deposited the muds of the Blue Bottom. 

Age and Correlation. 

Neai- Ross the beds luider consideration contain fossils which render their Middle or 
Upper Miocene age fairly certain,* and they may with some degree of confidence be correlated 
with the lowest beds of the Blue Bottom Formation of the Hokitika Bulletin. The blue clays 
seen behind the Ross United Company's open pit and at McLcod Terrace are evidently the 
equivalents of the upper more characteristic part of the Blue Bottom. 

Elsewhere, though often containing remains of Mollusca and Foraminifera, the beds do not 
yield characteristic fossils, whilst the varying conditions under which the several isolated 
outcrops were laid down renders the correlation of the various exposures with one another 
at times somewhat doubtftd. Wlxen necessary, the reasons for the correlations made in this 
chapter -will be given in connection with the description of each area imder the heading of 
" General Petrology." 

Distribution. 

Like the Koiterangi, the Upper Miocene beds have lost considerably by denudation, 
whilst areas of uncertain extent have been down-faulted, and covered by glacial and fluviatile 
deposits. 

The exposures are all in the Totara Survey District, within a few miles of Mount Green- 
laud. The beds are well seen south-east of Ross in the lower valleys of Donnelly, Bayley, 
and Coal creeks. An irregular fault-involved patch appears on the west side of the Totara 

* Hector : " Detailed Catalogue and Guide to the Geological Exhibits, New Zealaud Court,, Indian 
and Colonial Exhibition, London, 188G," p. 49. McKay : " Geological Explorations of the Northern Part of 
Westland," Mines Report, 1893, C.-3, p. 170. 



108 

River, apparently clinging to the slopes of Malfroy Spur from Stony Grvdly southward for 
fully a mile. A very small patch outcrops near the head of Harvey Creek, not far from 
Moyes Hill, at an elevatio}i of 925 ft. A long, rather narrow patch or series of patches out- 
crops along the Momit Greenland track north and south of Flagstaff Hill, at elevations of 
900 ft. to 1,100 ft. There are several small outcrops in the valley of Clear or Donoghue Creek, 
south of Ross, at various elevations. On the east side of the Mikonui Valley there are 
several outcrops between Redman Creek and Wilson Creek, whilst on the west side there is a 
good exposure at McLeod's Terrace Sluicing Claim. Undoubtedly the whole area from Clear 
Creek to Mcl^eod Terrace, and perhaps further west, is underlain bv beds of this formation : 
but the various outcrops are practically cliff-faces capped by fluviatile or morainic material, 
which obscures their lateral extension. 

There are two other areas assigned to the X'pper Miocene of slightly doubtful cliaracter. 
One is indicated by two or three small outcrops of calcareous gritty rocks in Smvth Creek and 
the Totara River. It occupies part of the low comitry south-east of Totara Saddle, and is 
close to the line of the great re\'ersed fault defining the western limit of the Arahura Series. 
Owing to the extreme poorness of the outcrops in this debris-smothered locality, the bound- 
aries shown on the map are necessarily rough. 

The otlier area, which affoids much better exposures, is along the same line south of the 
Mikonui, and was doubtless once connected with the Totara River outcrops, but in the inter- 
vening valley the beds have been destroyed by denuding agencies. 

Structurk. 

The typical beds near Ross are highly faulted, and strike in all directions from north and 
south to east and west. The dip is to almost all points of the compass, and varies from a few 
degrees to verticality. In the Hatter Creek locality (Totara Valley) the beds generally strike 
about north and south, and dip at low angles to the east. In one place they seem to strike north 
of west andxiip to the south. 

In the Upper Totara Valley the strike of the rocks assigned to the beds under consider- 
ation appears to be from 200° to 230°, and the dip is to the south-east. 

In the area south of the Mikonui, near the alpine chain, the strike-bearing is from 231° 
to 248°, and the dip to the south-east, at angles of from 15° to 85°. Both here and in the last 
locaUty the Upper Miocene beds have been more or less in\ olved in the great reversed fault 
which forms the western boundary of the Alps. 

Along the Mount Greenland track near Flagstaff Hill a strike of about north and south 
was observed, with a dip to the west of 10° to 25°. 

In the Clear Creek outcrops and on the east side of the Mikonui the beds are generally 
nearly horizontal. At McLeod's Terrace Sluicing Claim, however, the blue clays strike from 
west of north to east of south, on a bearing of 336°, and have a dip of 55° to west-south-west, 
whilst half a mile to the north similar beds have a strike of 346°, and dip at an angle of 22° 
to the south of west. 

The peculiar disposition of the Upper Miocene strata — here in low-lying coimtrj% 
close bv on comparatively high ridges — and their erratic strike and dip, bear effective witness 
to the amount and modern character of the faulting which has taken place in the Ross district. 

Paleontology. 

The lowest beds of the Ross area as they appear in Coal Creek are largely of marine origin, 
but one horizon contains plant-remains which have in places accumulated to form small irre- 
gular coal-seams. Higher in the sequence are beds with many fucoid casts, then come soft 
brown sandstones with numerous casts of lamellibranch shells, which bear the impress of 
coarse concentric ribs, and resemble a species of Venus. These are best seen near the junction 
of Bay ley and Donnelly creeks. There are calcareous la\ers in Coal Creek containijig uumerourt 



109 

shell-remains, amongst which may be recognised Panopea zelandica, Scalaria sp., Dentalium 
irregidare{i). Petiincihis (Glycmieris) sp., Carditxi sp., Nucula sp. Unfortunately, all the 
recognisable specmiens were from loose boulders, so that the exact horizon of an\- one is open 
to doubt. The Nucxda was found also at Redman Creek, again only in loose boulders. 

The microscopic sections made of the various rocks from the Totara-Smyth Creek area 
reveal the presence of Foranunifera, and fragments of organisms which probably represent 
Mollusca, Brachiopoda. and calcareous algae. The Foraminifera include one or more species of 
Ulubigerina (probal)l\- including G. comiUimerata), with Laqena. Discorhina, Nvdosaria, Rotalia, 
LingulinaC). Vngnmlitxi ((recta), Detitalina or a similar genus, and probably several other 
genera. 

The calcareous rock forming the lowest bed of the area on the south side of the Mikonui 
contains a number of fragments of bivalve-shells which are seldom, if ever, specifically 
or even generically recognisable. 

fxKNKRAL Characters. 

Owing to the local variations in lithological character and other considerations, it will 
be best to describe the several sections as exposed in different localities in an apparently 
irregular order. 

The area on the south side of the Upper Mikonui Valley has as its lowest bed the grey 
calcareous mudstonc with molluscan remains which is mentioned above. It is well seeji in Slate 
Creek and its tributaiy Pothole Creek, where it has a thickness of 200 ft. or 300 ft. At Slate 
Creek it forms a cliff of some height near the falls, and seems to rest both on granite and on 
grauwacke ; at Pothole Creek the ujideriying rock is jiot seen. The mudstone has coarse 
layers, which resemble, and in fact are. grauwacke. There are occasional small pebbles m 
it, mostly of grauwacke, a few of granite. The latter fact is of importance, for this is the 
oldest bed in the Mikonui Subdivision which contains any material derived from the granitic 
rocks now exposed over a large area. 

Above the nmdstone there is seen in Pothole Creek a considerable thickness of conglo- 
rnerat*', m which the stream has worn numerous potholes. The high fall of the stream is 
over this rock. It consists of rounded pebbles of granite and grauwacke. the former pre- 
dominating, both evidently derived from the slopes of Mount Rangitoto. The matrix, of a 
gre^-ish colour, is composetl of rock-grams of various sizes, largely quartz and feldspar, with 
possibly some biotite and a small amount of ver\' fine material. 

The presence of calcite, as shown by the abundant effervescence with dilute hydrochloric 
acid, indicates probable shell-remains, and therefore formation of the conglomerate under 
fiuvio-marine conditions. 

The absence of a basal conglomerate and the presence of granite pebbles in this and the 
underlying beds are considered to differentiate them from the Koiterangi Series. 

The absence of mica and gneissic schist is also significant. Had anything like the present 
topography prevailed in the area — that is. had the Alps at that time reached their present 
height — it is difficult to see how these rocks could have failed to be present, for this conglomerate 
is in close proximity to the present western margin of the alpine area. A high hill of gneissic 
schist rises close by, and within three miles is a mica-schist peak rising 4,000 feet above the 
conglomerate outcrops. 

The grauwacke-granite conglomerate passes upward into a white, gi'itty, micaceous 
sandstone, which outcrops along the upper course of Slate Creek to near Mair Saddle. Though 
quite devoid of shell-remains, it is calcareous in places, and probably represents an old beach. 

About two miles to the north-east of the area just described are the .small, unsatisfactory 
outcrops in Smyth Creek and the Upper Totara River. In this locality these streams run 
through nearly fiat gravel-covered country, and have cut in the gravels rather deep channels 
in which rock-outcrops appear towards the lower slopes of Bald Hill Range. The exposures 
consist of a coarse grauwacke, or consolidated arkositic rock, more or less calcareous, and in 



110 

one specimen highly so. Aside from the carbonate of lime, the constituents of this coarse gritty 
rock have been largely derived from a granitic area, and are essentially the same as those 
of the matrix of the conglomerate from Pothole Creek. The coarse grauwacke grades into a 
finer-grained rock, consisting largely of quartz, and therefore almost a sandstone, while near 
the head of Smyth Creek the upper part of the exposure is almost an argillite. 

Considerable outcrops of a loosely consolidated sandstone v-isible in Totara River were 
at the time of observation thought to belong to the Pleistocene drifts, but it is possible these 
correspond to the gritty sandstone of Slate Creek. 

At Ross the lowest beds referred to the Upper Miocene are seen in Coal Creek, and consist 
of hard, slightly calcareous, fossiliferous sandstones, which rest (through faulting) on or against 
grauwacke. At one point they are succeeded downwards by the Hodson Creek hmestoue, 
already described as of probable Koiterangi age. Near the mouth of Coal Creek the beds 
pass on the south side into quite loose white or iron-stained sands, which again are succeeded 
by firmer brown sandstone. Pebbly layers in this enable the strike and dip to be recognised. 

On the west side of Donnelly Creek the outcrop furthest up the creek is a soft sandstone 
containing fucoidal remains. Near the foot-bridge opposite Bayley Creek there is a remarkable 
layer of granite boulders nearly 1 ft. in diameter in the bro-wTi sandstone. This and other 
similar but finer pebble layers enable the dip to be ascertained. Beliind^the Ross United 
Company's old workings blue clays corresponding to those of the Blue Bottom appear. 

The outcrops of Upper Miocene beds in the Totara Valley, at the head of Harvey Creek, 
and on the Mount Greenland track, consist of brown slightly consolidated sandstone, with a few 
fine pebbly layers. 

The material composing the numerous outcrops on the east side of the Lower Mtkonui, 
in Clear Creek. &c., is also a soft sandstone, but the colour is generally a greyish or yellowish 
white. 

At McLeod's Terrace Sluicing Claim the Upper Miocene beds are seen to consist of the 
same sandstone, followed by well-stratified brown and blue clays, which correspond in character 
to the Blue Bottom clays. 

Special Petrology. 

1. From Slate Creek, south of Gribben Flat (Upper Mikonui). 

The hand-specimen is a dark-grey, fine-grained argillite or mudstone, which effervesces 
abundantly with cold dilute hydrochloric acid. 

Under the microscope the section consists largely of greyish-brown, nearly opaque, stringy 
matter, which is almost white by reflected light, and of the character generally referred to as 
kaolinitic, with some calcite forming foraminiferal tests, and numerous small angular quartz- 
grains. There are also one or two fragments of green hornblende, a little biotite, some green 
glauconite (probably), and a few grains of pyrite. 

The Foraminifera are nearly all detached globigerinal cells of one species, with an average 
diameter of about 0'12 mm., but there is also a larger species ; whilst Lagcna, Denialina or 
Nodosaria, and perhaps other genera, are also sparingly represented. The interior of all 
the tests is filled with so-called kaolinitic matter. 

Remarks. — The character of the rock and the presence of Foraminifera indicates deposi- 
tion under quiet-water conditions in a sheltered arm of the sea. 

2. From a small outcrop in Smyth Creek. 

The hand-specimen is a light-grey, micaceous, firmly consoUdated grauwacke. It effervesces 
markedly when moistened 'with cold dilute hydrochloric acid. 

The microscopic examination shows that it consists of closely packed and angular grains 
of quartz and various feldspars cemented by calcite, mica, a httle viridite, and perhaps one 
or two fragments of garnet, zircon, &c. 



Ill 

The feldspars consist of probable orthoclase, albite or an acid soda-lime feldspar, and a 
little microcline. The orthoclase is affected by decomposition along cleavage-planes, &c. ; 
the other feldspars are fresh. 

The calcite patches were closely examined for Foraminifera, with the result that a single 
nearly circular grain surrounded by a ring of impurities, which almost certainly represents 
a Globigerina, was discovered. 

The viridite is probably glauconite, and, if so, is also an indication of Foraminifera. 

The mica is mostly biotite, but a little muscovite is also present. Some half-bleached 
biotite with bent laminae is clearly original ; the rest is secondary. 

Remarks. — The quartz, feldspar, and original mica of this rock are evidently derived 
from a granite like that of Mount Rangitoto. The abundant cementing calcitic matrix, even 
apart from the doubtful foraminiferous test, connects it with the Tertiary marine beds. The 
rock might possibly be of Koiterangi age, but its field relations, and more particularly the 
granite-derived constituents, have lead to its being included in the Upper Miocene rocks. 

3. From outcrop in Smyth Creek, near granite. 

The hand-specimen is a medium-grained, grey, compact rock. Examination of a smooth 
surface with a lens shows Foraminifera, glauconite, &c. It effervesces strongly with dilute 
hydrochloric acid. 

Under the microscope the section is seen to consist of calcite formed from the remains 
of Foraminifera, &c., \nth numerous small angular or somewhat rounded grains of quartz, one 
or two scales of bleached biotite, some viridite, &c. There is a greater variety of Foraminifera 
than in the Koiterangi or Ross limestones. Globigerina are -numerous, and there are many 
other recognisable genera, including probably Discorbina, Nodosaria{'i.), Rotalia, Lingvlina{}.), 
and Vaginulina (? recta). Besides the Foraminifera there are organic structures quite 
recognisable by an expert which may represent Mollusca, Brachiopoda," and calcareous alg;e. 

Remarks. — Petrographically the rock might be called arenaceous Umestone. The micro- 
scopical examination by a competent palaeontologist of the organic structures preserved in 
it would without doubt afford valuable results. (See Plate XXIV. No. 3.) 

4. From same locality as No. 3. 

The hand-specimen is darker grey and of coarser grain than No. 3. It effervesces with 
cold dilute acid. 

Under the microscope it is seen to consist of numerous angular or partly rounded quartz- 
grains, with a good many fragments of feldspar and some half-bleached biotite, viridite, &c. 
The cementing media are chiefly calcite and pyrite, the former of which has strongly attacked 
many of the feldspar and more especially the quartz grains. 

The feldspar-fragments are of the same character as those in No. 2. 

The calcite was carefully examined for organic remains, but none could be certainly 
detected. The viridite, however, may be glauconite, and therefore suggests Foraminifera 
or other marine organisms. 

The presence of pyrite in some quantity shows that the rock has been subjected to foreign 
influences. It may be termed a grauwacke, the main constituents of which have been derived 
from a granitic area. 

• 
"). From Pothole Creek (tributary of Slate Creek). 

The hand-specimen is a harsh, gritty, rather compact rock, of a greenish-grey colour, 
which may be called a coarse-grained grauwacke. Scales of secondary mica are abundant 
on joint-surfaces, and the mass of the rock contains a good deal of glauconite. Treatment 
with cold dilute hydrochloric acid causes marked efiervescence. 



112 

Microscopic examination shows that the rock consists of angular grains of quartz and 
feldspar of the several species noted in No. 2, with numerous glauconitic grains and some 
pyrite. 

Although mica is so noticeable on the surface of the hand-specimen, it is almost absent 
from the bodv of the rock, the section showing onlv one or two scales of secondary 
biotite. 

Calcite i^ fairly plentiful as a cementing medium, and. as in several other sections, has 
invaded both the feldspars and the quartz. 

Remarks. — Again the main constituents of the rock must be noted as coming from a 
granitic area. The presence of calcite and of glauconite grains indicates that the rock, like 
the others of the series, once contained Foraminifera and perhaps other marine organisms. 





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118 



CHAPTER X. 



Introduction 


. 113 


I. Moutere Gravels (Early Pliocene) 


. 113 


General Account 


. 113 


Age and Correlation 


. 114 


Distribution 


114 


Structure 


. 114 


General Characters 


114 


Origin . . 


. 114 



PLIOCENE, PLEISTOCENE, AND RECENT BEDS. 



Page 
II. Late Pliocene and Pleistocene Deposits 115 
(a.) Morainic and Flu vio - glacial 

Gravels . . 115 

(6.) Fliiviatile Gravels . . .. 118 

(c.) Marine Gravels .. ..118 

III. Recent Deposits .. ..118 

(a.) Glacial and Fluvio-glacial .. 118 
(b.) Fluviatile and Lacustrine .. 118 
(c.) Marine 119 

(d.) Talus .119 

Introduotton. 

At the end of the Miocene period depression of the land ceased, and general rapid elevation 
began in almost all parts of New Zealand as we now know it. In the Mikonui area there, 
ensued at this time great changes in the land-forms, caused not only by the general elevation, 
but also by the appearance of the Southern Alps as a mountain-chain of the first magnitude, 
and by faulting on a huge scale, accompanied by subsidence, which caused the disappearance 
of nearly all the land to the westward. A new major cycle of erosion set in, which has only 
just reached the stage of maturity, and is still actively proceeding. The deposits of this half- 
completed cycle of erosion are, with the exception of lake-silts and sea-sands, almost entirely 
of a coarse character. They will be discussed under the headings of (I) Moutere Gravels (Early 
Pliocene) ; (II) Lat« Pliocene and Pleistocene Deposits ; (III) Recent Deposits. 

I. Moutere Gravels (Early Pliocene). 
General Account. 

Owing to land-elevation the beginning of the Pliocene was marked in Westland and 
Nelson, as in many other parts of New Zealand, by a very general denudation of the earlier 
Tertiary beds — that is, of the Koiterangi Series and of the Upper Miocene beds. The finer 
material was swept out to sea, but the coarser debris remained on the land to form gravel- 
deposits of peculiar character. These can be recognised at intervals along a line from Ross 
to Nelson, and have been called by Cox and McKay the " Moutere Gravels," owing to their 
extensive development in the lower watershed of the present Moutere River. They are 
characterized by the extremely decomposed nature of the constituent pebbles and finer mate- 
rial, from which it arises that they are generally very clayey, and are stained yellow or brown 
by liberated oxide of iron. This feature is due to their being composed very largely of 
Tcassorted pebbles from the conglomerates of the coal-measures, which were thus compelled 
to do duty twice over in fornxing coarse fragmental deposits. 

In Westland these ancient gravels form the true Old Man Bottom of the gold-miners. 
They have been much denuded, and, as a consequence, in places enter largely into newer beds, 
to which they give their characteristic appearance. Hence the name of " Old Man Bottom " 
is applied by the miners to these also. The Humphrey's Gully Beds* are probably composed 
in great part of reassorted Moutere or Old Man gravels, and may be of more recent date 
than is generally supposed. 



• See McKay : " Geological Explorations of the Northern Part of Westland," Mines Report, 1893, 
C.-3, pp. 168-170 ; also Bull. No. 1 (New Series), N.Z.G.S., 1906, pp. 88-8!», for descriptions of these beds. 



8 — MiicoDui. 



114 

Age and Correlation. 

McKay considers that the Moutere Gravels succeed the Blue Bottom vnih a very slight 
degree of unconformity, and therefore classifies them as Upper Miocene and Older Pliocene.* 
In this bulletin the evident setting-in of a newer cycle of erosion, with rapid progress towards 
the modem land-forms, is thought to justify their complete separation in time from the Miocene 
beds. On the other hand, the characteristic Uthological characters and the stratigraphical 
evidence seem fully to confirm McKay's correlation of the Westland exposures with the Mou- 
tere Gravels of Nelson. 

Distribution. 

In the Mikonui Subdivision the exposures of the Moutere Gravels are of small extent. 
The principal outcrop forms the bulk of the low ridge just north of Ross over -which the main 
road passes, and the old terrace which extends from this ridge to the east for over a mile. 
The same ancient gravels may be present in the low hillsides near the Ross United shaft. It 
is possible, however, that these are more modern gravels, containing much material from the 
Moutere beds. A less doubtful outcrop of the latter appears on the eastern bank of the 
Mikonui River, just below the foot-bridge. Here they are seen for two or three chains along 
the base of a cliff formed of coarse modern fluviatile gravel. 

From the general appearance of pebbles and even large masses derived from them in 
many of the older flu\'iatile and morainic deposits, it is apparent that the Moutere Gravels 
once had a much wider distribution in the Mikonui area than at present. 

Structure. 

The various exposures of the Moutere Gravels show a poorly developed stratification, 
which is usually almost disguised by the clayey products of their decomposition. As seen on 
the roadside near the top of the low ridge north of Ross, they appear to have a dip of a few 
degrees to the north-west. Elsewhere dip is not apparent. 

General Characters. 

As already intimated, the Moutere Gravels within the subdivision are composed largely of 
much-decomposed debris derived from the older Tertiary beds, more especially the Koiterangi 
conglomerates. Since the last-named rocks are composed almost entirely of grauwacke, this 
becomes also the most abundant constituent of the Moutere beds. Granite is somewhat 
sparingly represented, and since the individual boulders and pebbles are generally rotten, it 
may be concluded that they have come to a great extent from the Miocene conglomerates. 
Schist and the other distinctive rocks of the main alpine chain were not observed, and may 
be entirely absent. 

It is true that the grauwackes, so far as their lithological characters are concerned, may 
have come from the main divide, but the ab,sence of the intermediate schists is a fatal objec- 
tion, and other reasons have already been given for deriving them originally from the Green- 
land Series by way of the Koiterangi conglomerates. 

Bi side grauwacke and granite, argillite and quartz were the only other rocks observed 
among the pebbles of the Moutere Gravels. The matrix in which the pebbles are embedded 
consists of clayey material, derived chiefly from the weathered grauwacke pebbles, and much 
stained by oxides of iron. 

Origin. 

It has been shown by McKay that the Moutere or Old Man gravels were the proximate 
source of the greater part of the alluvial gold found in Northern Westland. The question 
of their origin is therefore a matter of considerable importance. Sir James Hector, in his 



•'Geological E.Kplorations of the Northern Part of Westland," Mines Report, 1893, C.-3, p. 167. 



115 

leport of 1866-67, pointed out that the older alluvial deposits of Wcstlaud were the first formed 
drifts of an ancient river which ran in an old valley which extends south-west from Blbd 
Bay, and is obliquely cut ofE by the sea-coast between the mouth of the Teremakau and Okarito.* 
In his report of 1893 McKay discussed in an able manner the whole question concerning the 
origin of the Moutere Gravels. The conclusions he came to may be summarised as follows :— 

1. On account of their lithological similarities the various exposures of the Moutere Gravels 

from Ross to Nelson cannot well be the product of several streams, nor are they 
littoral deposits, but were deposited by one great river which probably ran north- 
east from some point south of Ross to Blind Bay. 

2. There was necessarily high land to the west of the present coast of Westland during 

the time this river existed. 

3. The Southern Alps did not then exist — at least, in their present form. 

4. Consequently, at the time the Moutere Gravels were being formed the configuration and 

physical characteristics of the South Island of New Zealand were quite different 
from those of the present day.f 

Although McKay may not have given due weight to any alternative views,J it does not 
follow that his conclusions are wrong, and it must be admitted that the bulk of the evidence 
is in their favour. For this reason the Pliocene age of the hypothetical Moutere River may 
be at least provisionally accepted. 

Since the supposed Moutere River ran from south-west to north-east, it follows that the 
old gravels in the neighbourhood of Ross were transported from the south. It has already 
been said that they were largely derived from the conglomerates of the coal-measures, which in 
their turn were derived from the grauwackes and slates of the Greenland Series. Primarily, 
then, the Moutere Gravels were derived from the rocks of this series, and, as regards the 
beds near Ross, the probability is that the constituent pebbles originated from an area of 
Greenland rocks well to the southward of that district. 

II. Late Pliocene and Pleistocene Deposits. 
(a.) Morainic and Fluvio-glacial Gravels. 

The morainic deposits of Westland are evidently indissolubly connected in origin with 
the great alpine chain, from which they derive almost the whole of the material of which they 
are composed. 

Soon after the deposition of the Moutere Gravels, if not before, the mountain -range had 
attained a height above the permanent snow-line. About this time the land to the westward 
of the present coast-line disappeared. The sheltering western land gone, precipitation in- 
creased, and the snowfall must then have at least equalled that of modern times. Towards 
the end of the Pliocene the Alps had probably reached their maximum elevation, for though 
there may have been further elevation after that time, denudation has more than kept pace with 
elevation. As has been pointed out in Chapter III, the area of the snowfields was very 
much greater than in later times, because erosion of the valleys had not progressed to a great 
extent. It can therefore be easily understood, without resorting to any theory of a glacial 
epoch, why vast glaciers arose, which advanced into the low country, and south of the Mikonui 
reached the present coast-line. Moreover, Von Haast§ and Hutton have advanced sound 
arguments against the likelihood of any Late Tertiary glacial epoch in New Zealand. 

♦ These statements appear in JIcKay's report, entitled " Geological Explorations of the Northern Part 
of Westland," .Mines Report, 1893, C.-3. p. 174. The original has not been seen by the writer. See also, how- 
ever. Hector: '•Abstract Report on the Progress of the Geological Survey of New Zealand during 186(5-7," 
p. 13, and "'On Mining in New Zealand," Trans, vol. ii. 1869, p. 369. 

t Iak. cit.. pp. 174-82. 

X In 1896 he seems to have somewhat modified his views. See Gordon and McKay : " Report on Minine 
Re.<ierves, Westland and Nelson," Mines Report, 1896, C.-9, p. 5. 

§ " Geology of Canterbury and Westland," 1879, pp. 371-383, 

8'— Mikonui 



116 

For a comparatively long period, probably nearly to the end of the Pleistocene, the 
glaciers occupied much of the present lowland district. During this period there may have 
been minor retreats, followed by fresh advances, but all the time the glaciers were busy deposit- 
ing their morainic burdens. Then began a final retreat into the heart of the mountains which 
seems to have been comparatively rapid, for the deposits of the modem glaciers are quite 
separated from the older morainic debris of the lowlands. 

Much of the material brought down by the glaciers was to some extent sorted and dis- 
tributed by running water. This action took place partly under the ice, partly in the vicinity 
of the ice-front, but all the resulting deposits may be included under the term of fluvio-glacial. 
Before the advance of the glaciers, and also during their retreat, a certain amount of material 
was transported considerable distances by water alone : these form the fluviatile deposits. 
Some material also was finally sorted by marine action, forming deposits of a third class. 

Age and Correlation. — As will have been gleaned from Chapter III, the glacial and fluvio- 
glacial deposits of the extended glacier period are considered to be of Late Pliocene and Pleisto- 
cene age. The fluviatile deposits which immediately preceded and followed are therefore 
Middle or Late PUocene and Late Pleistocene. The marine deposits now visible are of little 
importance or extent, and may be classed as Late Pleistocene. Practically deposition of all 
three classes of material must have been proceeding simultaneously, but the definitions given 
include all deposits now exposed. 

Hutton, however, considered that the deposits of the extended glacier period were all 
of Pliocene age,* whilst Von Haast classes them as Upper and Post Pliocene.f It seems im- 
possible to apply the age views of the former writer to Westland, but by a slight alteration 
of the terminology used in this bulletin a general agreement with Von Haast results. 

There is no difficulty in correlating the deposits under discussion with the similar material 
of which great masses are found extending over the western portions of the Canterbury Plains. 
They may also be correlated with similar though smaller deposits in Nelson, with the morainic 
deposits of Central Otago, and more doubtfully with the old moraine which appears on the 
east side of the Taieri Plain near Otakaia and Henley. 

Distribution and Lithological Character. — The most northerly area of morainic material 
is on the eastern margin of the Kokatahi-Koiterangi Plain between Doughboy Hill and the 
junction of the Toaroha River mth the Kokatahi. West and north of Lake Arthur, moraine 
extends over a considerable area of hillocky country, containing several little ponds. It is 
composed almost entirely of mica-schist boulders, in places not in the least ice or water worn, 
piled indiscriminately together without any small material. Several small ridges and hillocks 
between Lake Arthur and Doughboy HUl are evidently of glacial or fluvio-glacial origin, and 
beneath the modern river-gravels of the plain are doubtless continuous with the morainic 
debris around Lake Arthur. These deposits appear to be due to a branch of the ancient Hoki- 
tika Glacier, which passed behind Doughboy Hill. 

Part of the debris deposited by the old Hokitika Glacier extends over a small area along 
the northern boundary of the Totara Survey District. By far the greater part of the Hokitika 
moraine occurs in the Mahinapua Survey District, and was described in the Hokitika Bul- 
letin.J The debris in this area is largely granitic, and appears to have been derived mainly 
from the neighbourhood of Doctor Hill. 

Near Ross, fluvio-glacial gravels, with some purely morainic material, appear in the 
Mont d'Or Claim, and extend as a fringing deposit between the hills and the coastal plain 
west and south-west, but not without some interruption, to near Redman Creek. 

At the Mont d'Or Claim probably three-fourths of the debris has been derived from the 
Moutere Gravels, and consists mainly of decomposed grauwacke, with rotten granite in small 
quantity, and a considerable amount of yellow clayey material. The remainder consists 

* " On the Geological History of New Zealand," Trans. N.Z. Inst., vol. xxxii, 1899, pp. 173-178. 
t " Geology of Canterbury and Westland," 1879, p. 251. 
I BuU. No. 1 (New Series), N.Z.G.S., 1906, pp. 86, 90, 93, 



117 

largely of Greenland grauwacke, with some fresh granite, mica-schist, and other rocks from 
the alpine divide. 

On the west side of the Mikonui is a much larger area of similar material, which extends 
with a terraced margin from a little south of McLeod's Terrace Sluicing Claim to within a mile 
of the sea, where it passes into marhie gravels. These two last areas are due to the deposits 
of the old Mikonui Glacier. 

A small isolated patch of morainic material which occurs about half-way along the track 
to Mount Greenland from Ross is apparently lateral moraine deposited by the last-named 
glacier. 

A remarkable pile of ice-borne debris forms Bold Head, the isolated terminal moraine of the 
old Waitaha Glacier. It is about two miles long, half a mile wdde, and over 400 ft. high. 
Here the morainic deposits, unlike those of the Mikonui Glacier, are composed almost entirely 
of schist, grauwacke, and other rocks derived from the alpine chain, with a Uttle granite. 
Some of the boulders are of extraordinary size. Bold Head has been partly destroyed by 
the sea, and an excellent section is furnished by the cHff-face which has resulted. This shows 
it to consist very largely of irregularly distributed, but water-sorted, material. A detailed and 
most interesting account of this moraine is given by Von Haast,* to whom the reader may 
therefore be referred for further information. 

Long ndges of morainic material appear on either side of the Waitaha Valley, and curve 
round so as almost to meet at the bridge about two miles from the sea. The boulders are 
chiefly derived from the main divide, but granite is well represented, and there is also a certain 
amount of Greenland grauwacke. 

The deposits of the ancient Wanganui Glacier are of the greatest importance and interest. 
On the north side of the Wanganui the morainic and fluvio-glacial gravels cover the greater 
part of the country south of Duffer Creek. To some extent the purely glacial deposits are 
shrouded by modern river-gravels almost Huvio-glacial in character, for they must have been 
deposited during the glacial retreat. Near Lake lanthe the morainic hills rise to a height of 
1,095 ft. above sea-level. How far below sea-level they extend we have no means of judging, 
but not improbably it is little less than the extent above. The section shown by the sea-chff 
from Wanganui Bluff to Cliffy Head is even more remarkable than that of Bold Head, and 
we are again indebted to Von Haast for a graphic account.f The boulders represented in 
the Wanganui moraine are principally schistose rocks and grauwacke from the alpine chain. 
To a large extent they are the rocks appearing on or near the present main divide, but it is 
reasonable to conclude that in part they were derived from the less metamorphic rocks over- 
lying the mica-schists, which have now been entirely removed by denudation. 

Small patches of morainic material appear here and there among the low hills of the Totara 
Survey District — for example, east of Doctor Hill, on the east side of Malfroy Spur, and south 
of Totara »Saddle. In the last locality the boulders are mainly mica-schist. There is, however, 
surprisingly little morainic debris in the foothill area, considering that there are several wide 
valleys which have certainly been occupied by glaciers, and even the hills have probably been 
almost all ice- smothered. 

All the river-valleys within the main mountain-system contain at various points con- 
siderable deposits which are partly lateral moraine left by the retreating glaciers, with fluvio- 
glacial gravels spread by water in front of the retreating ice-face, and partly talus or fan deposits 
which have accumulated at the same time. These are again overlain by more modern de- 
posits, generally of coarse character, so that it often becomes impossible satisfactorily to 
separate the various components. The later deposits are composed of the same materials 
as the earlier, so that the lack of distinguishing features is of little importance. 



» " Geology of Canterbury and Westland," 1879, pp. 93-94, 393. 
t Loc. cit., pp. 393-395. 



118 

{b.) Fluviatile Gravels. 
(Jf the fluviatile gravels deposited prior to the advance of the glaciers little can be seen 
in the Mikonui Subdivision, because they are for the most part entirely buried by the glacial 
debris. The bottom on which the Mont d'Or Sluicing Claim (Ross) is working is probably of this 
character. The Late Pleistocene gravels laid down during the retreat of the glaciers have 
been almost completely covered by newer river-gravels. The coarse gravels which occur on 
Purcell Ridge, near the head of Hitchin Creek, may be of this age. They were probably de- 
posited by streams from Mount Allen before the neighbouring valleys were entirely clear of 
ice. Of similar origin may be the gravels on Murray Saddle, east of Mount Misers-, and on 
Truran Pass, between the Kakapotahi and Tuke rivers. 

(c.) Marine Gravels. 

Of the marine deposits of the extended glacier period little can be seen. Before the glaciers 
advanced into the lowland country much water-borne gravel must have reached the sea, which 
at that time probably extended almost to the foot of the mountains, and much ice-carried 
debris dumped into the sea was no doubt more or less assorted by the waves. All this material 
is either still below sea-level or is covered by the newer deposits. To the Late Pleistocene 
may perhaps be referred the gravels forming the seaward terminations of the morainic or 
fluvio-glacial ridges near the mouths of the Waitaha and Mikonui rivers. 

The pebbles of these marine terraces are naturally of the same character as the 
boulders of the respective morainic ridges, and differ from them only in their smaller size 
and water-worn appearance. 

III. Recent Deposits. 

(a.) Glacial and Fluvio-glacial. 

At the heads of the intra-montane valleys the most recent morainic deposits are easily 
recognised in front of the still-retreating glaciers, together with, fluvio-glacial terraces, &c. 
Coming to the glaciers themselves, we find that while good terminal moraines may appear, 
lately formed lateral moraines, except in the case of the Evans Glacier, are not very well 
developed. The lower parts of the larger glaciers are covered by debris which often hides the 
ice from side to side, while the upper parts are perhaps quite free from surface moraine. 

In the maps which accompany this report the recent glacial deposits are coloured in the 
same way as the older morainic gravels, but are distinguished by a conventional sign.* 

{b.) Fluviatile and Lacustrine. 

Modern fluviatile gravels are widely spread over the lowlands, forming the surfaces of 
the plains, river-terraces, &c. In the mountain districts the various river-flats are, of course, 
similarly covered, and are fringed by one or more terraces, sometimes composed of fairly 
fine material. Coarse gravels are commonly seen, often at considerable heights where the 
valleys are at all open, and sometimes even where they are very narrow. 

Fan deposits have been sufficiently particularised in the chapter on physical geography. 

Part of the modem coastal plain is, as regards its surface, of fluviatile origin. 

Since the principal plains and perhaps most of the river-flats were once lakes, lacustrine 
deposits must underhe the river-gravels. In the main these are probably gravels. 

At several places lake or pond deposits have been seen, in all cases consisting of a fine 
brown silt of unknowm depth. These spots are : Murray Saddle, the upper valley of Falls 
Creek, Happy Valley (Kakapotahi River), and the Waitaha Valley near Sugarloaf Hill. 

The fluviatile gravels consist not only of material brought down from the mountain since 
the retreat of the glaciers, but also of reassorted older debris, and more particularly ol 
morainic and fluvio-glacial gravels. 



In one locality (near Lake Arthur) this sign has been placed on older glacial deposits. 



119 

(c.) Marine. 

Except as previously stated, the narrow coastal plain from the mouth of the Totara south- 
ward to the Raho-Taiepa has been built by the sea with gravels and sands brought down 
by the rivers. It is perhaps being slowly added to at the mouth of the Mikonui. The small 
patch of flat on the north side of the Wanganui was partly destroyed by the sea many years 
ago. The low sandhills and the beach were described in Chapter IV. 

The beach-sands consist mainly of quartz. Magnetite is a noticeable constituent, whilst 
garnet and zircon are fairly common, the former being especially abundant on the beach near 
Ross. More or less fine gold is always associated with the magnetite. 

(d.) Talus. 
The talus deposits among the mountains are often of great extent. The shp deposits of the 
Waitaha Valley, &c., may also be brought under this head ; but since they, as well as the talus 
deposits, were described in Chapter IV, no further mention is required. 



m 



CHAPTEK XI. 



THE POUNAMU OR SERPENTINE FORMATION. 





Page 




FitjZ 


Content 


.. 120 


General Petrology — continued. 




Mode of Occurrence . . 


. . 120 


(3.) Serpentine-schist 


. 122 


Age and Correlation . . 


. . 120 


(4.) Talc-serpentine and Talc-rock 


. 123 


Distribution 


.. 121 


(5.) Miscellaneous Rocks 


. 123 


General Petrology 


.. 121 


Special Petrology 


. 124 


(1.) Serpentine-dunite 


. . 121 


Metamorphic Influence 


. 128 


(2.) Serpentine 


. . 122 






- 


Content. 





As developed hi the Mikouui Subdivision, the Pounamu Formation consists principally of 
serpentine-dunite, nearly pure serpentine, serpentine-schist, and impure talc. These rocks 
are the hydrated and otherwise altered representatives of certain ultra-basic rocks which 
have been intruded into the Arahura Series. The mineral nephrite, or pounamu of the Maoris, 
occurs very sparingly within the subdivision, and could not be located in situ, though in one 
place there were foiuid primary inclusions or segregations from the original magma of a 
white somewhat fibrous amphibole of the same composition as nephrite, though of very 
different appearance.* The rocks of the formation also exhibit a considerable variety of 
secondary minerals, chief among which are talc, asbestos, epidote, actinolite, tremolite, 
quartz, calcite, dolomite, magnesite, ankerite, magnetite, pyrite, &c. 

In the report on the Hokitika Subdivision certain altered rocks of the Arahura Series 
were, for convenience' sake, described with the Pounamu Formation, but in this bulletin the 
corresponding rocks have been mentioned with the other members of the Arahura Series. 

Mode of Occurrence. 

The rocks of the Pounamu Formation occur in the Mikonui Subdivision in the same way 
as further north — that is, they form sill-like sheets of varying dimensions in the middle schists 
of the Arahura Series. As a rule, the intrusions are sills running parallel to the stratification, 
but in one or two instances they seem to cut at acute angles across the strike of the enclosing 
rocks. The exposures range from 100 yards to a mile or more in length, and have a thickness 
varying from a few yards to about 5 chains. They occur in several parallel belts, which may 
average a quarter of a mile apart. Not uncommonly an outcrop disappears somewhat abruptly, 
but ultra-basic rock often reappears a few chains further on, and it is usually a matter of doubt 
whether the outcrops are continuous in the surface zone or not. Sometimes there is immis- 
takably a break in surface continuity, though the exposures are probably connected below. 

Age and Correlation. 

The age of the Pounamti Formation is uncertain. From the mode of occurrence alone 
it would be reasonable to conclude that the ultra-basic intrusions took place after the rocks of 
the Arahura Series had been strongly folded. When, however, the constant association of 
serpentine wdth folded moimtains and its ultra-basic and therefore deep-seated character 
are taken into account, it seems very probable that the Pounamu rocks were intruded during 
a motmtain-building period. The available evidence points to the first uplift of the Alps 



* See pp. 126-127. 



121 

as a mountain-chain in Early Tertiary time, and there was a further strong upward movement 
just after the Miocene. 

The occurrence of pebbles from the Pounaniu Formation in the upper part of the Blue 
Bottom* negatives the possibility of post-Miocene age, which on other grounds is certainly 
unlikely, and the ultra-basic intnisions may therefore somewhat tentatively be referred to 
the Early Tertiary. Whether they preceded or followed the Tuhua rocks is uncertain. 

The Pounamu Formation of North Westland may be correlated, perhaps doubtfully, with 
the Red Hill serpentine of the Jackson Bay district in South Westland. Somewhat more 
doubtful, but not altogether improbable, is a correlation with the isolated dyke of serpentine 
found in the Cromwell Subdivision.! 

Distribution. 
As already mentioned, the rocks of the Pounamu Formation appear in the horizon of the 
middle schists. The most northerly outcrop in the subdivision is in the first gorge of the 
_ Kokatahi River, rather less than a quarter of a mile above the junction of Adamsou Creek. 
Possibly there are exposures to the north-east and south-west, on the slopes of Browning Range 
and The Pinnacle, but these could not be located. East and south of Mount Jiunbletop there 
are several outcrops of serpentine and talc occurring along two distinct lines. From the valley 
of the Holdtika near Serpentine Creek to the Cropp River there are numerous exposures, in 
which all the rocks of the formation are represented. These occur along three or four linos 
confined to a belt not a mile wide. Beyond the upper valley of the Cropp River the formation 
is not again seen till, in the valley of the Waitaha, east of Urquhart Knob, a small outcrop 
of serpentine makes its appearance. 

General Petrology. 

As a rule, with the exception of the soft talcose bands, the outcrops of the Pounamu Forma- 
tion stand out above the general level, owing to their weathering less readily thaji the more 
friable schists, and are easily recognised by their peculiar reddish-brown weathered surface. 
In the valley of Serpentine Creek there occurs a green, well-foliated serpentine, which has 
evidently been fault-crushed, J and more or less foliated talc is seen at the Whakarira Gorge 
(Kokatahi River) and on Jumblctop. Elsewhere the structure — at any rate, of the harder 
members — is only slightly schistose, though fault-movement among the associated talc-schists 
is nearly always apparent. 

The more or less complete metamorphism of the original ultra-basic rocks mav be con- 
sidered as caused by the heated solutions which influenced the neighbouring schists, and were 
no doubt the consequence, or rather the aftermath, of the igneous intrusions. The change 
produced is mainly one of hydration ; but iji the case of the talcs, though silica and magnesia 
are still the principal constituents, either more silica was introduced, or a considerable 
amount of magnesia was abstracted, the latter alternative being the more probable. With 
the magnesia went much of the iron, manganese, and chromium compoimds, but lime was 
often introduced in the form of carbonate, this latter change possibly at a later stage. 

The rocks of the Pounamu Formation may be further described under the headings 
of — (1) Serpentine-dunite, (2) serpentine, (3) serpentine-schist, (4) talc-serpentine and talc 
rock, (5) miscellaneous rocks occurring in small amount. 

(1.) Serpenthie-dunite. — Some of the large masses of rock which occur on the south-east 
slope of Mount Bowen are plainly, even at the first glance, fairly fresh. They present the 
usual broNvnish weathered surface, but on being broken are, on the whole, dark-coloured, 
with many light-green spots. A series of samples taken from one of the outcrops, and sliced 
for the microscope, shows that while the outer part of the sill is rather more than half serpen- 



♦ Bull. No. 1 (New Series), N.Z.G.S., 1906, p. 86. 
t BulL No. 5 (New Series), N.Z.G.S., 1908, p. 28. 
J See note at end of this chapter. 



122 

tine, about the centre there is much more olivine than serpentine. The other minerals present 
are magnetite, chromite or possible picotite, and pjTite, the last named in small quantity, 
and probably of secondary origin. The chromite does not occur as independent grains, but 
always as the core of a magnetite indi\'idual. Magnetite, sho%vTi by the analysis of the rock 
to be free from titanium, is much more plentiful, and occiirs in large shapeless masses and 
small grains, many of which show crystal outlines to some extent. Nearly all are perfectly 
fresh, as is shown by the bright metallic lustre. The olivine, which is slightly cloudy from 
impurities, in the least- altered section forms about four-fifths of the entire mass. Professor 
W. SoUas records the occurrence of augite (very rare) in a boulder of dunite from the Hoki- 
tika River, but this mineral was not observed in any of the serpentine-dunite sections.* 

The serpentine is to a large extent in laths, which cross one another more or less, and 
often have a tendency to a kind of fan structure, although, strictlv speaking, they seldom 
radiate from a well-marked centre. There is also an incUnation in some sections for the laths, 
though they are never quite parallel, to have one general direction. Where not in laths, the 
sei-pentine is in small, rather shapeless masses, or has a tendency to " net "' structure. 

The mesh structure which is so characteristic of the Lizard (Cornwall) serpentine is almost 
entirely absent from the completely sei-pentinised areas, notwithstanding that some of the 
nearly fiesh oUvines are breaking up into the rather irregular trapeziums characteristic of 
decomposing oUvme. The process of replacement normal to these rocks can be very clearly 
traced in the sections. Laths of serpentine grow right across the olivine crystals, generally 
starting from the margin, and as they advance the cracks and impurities of the olivine dis- 
appear in a wonderful way, so that the original structure is completely obliterated. The 
advancing laths generally fan out to a. considerable extent, and show some variation in 
polarisation colours, due probably to varj'ing thickness. The extinction of the serpentine 
laths is straight or nearly so, and the polarisation colours vary from steel-grey to a fairly bright 
yellow. The refractive index is noticeably above that of Canada balsam. Sometimes the 
indi\'idual laths show a delicate longitudinal parting, probably due to the serpentine 
advancing as a number of semi-independent fibres. The characters observed seem to be 
those of antigorite, except that laminated or foliated structure is not developed to any 
noticeable extent. (See Plate XXIV. No. L) 

Some of the Pounamu Formation exposures on Mount Bowen, and more especially those 
along the most easterly hne, are of serpentine-dunite. Where serpentine is well developed a 
number of other secondary minerals, including talc, asbestos, tremolite or actinoUte, 
magnetite in fine octahedi-al crystals, and pyrite, appear. 

(2.) Serpentine. — Several of the outcrops of the Pounamu Formation are of an almost 
pure serpentine. Commonly they have the same outward appearance as the serpentine- 
dunite. The broken surface is lighter coloured, usually greenish, has a greasy lustre, and 
generally shows some appearance of a schistose or fibrous structure. The sections show 
that the specimens consist almost wholly of serpentine, with some magnetite, a Uttle resi- 
dual olivine, augite. &c. Fairly pure serpentines are seen in the Upper Hokitika Valley 
and on Moimts Inframeta and Bowen. Loose boulders of antigoritic serpentine are common 
in the bed of the Cropp River. The serpentines are accompanied by a variety of secondary 
, minerals, including talc, asbestos, tremolite or actinolite, chlorite, magnesite, dolomite, 
calcite, magnetite in fine octahedrons, well-crystallized pyrite, epidote, quartz, &c. 

(3.) Serpentine-schist. — The rocks classed as serpentine-schist differ from the serpen- 
tine only in being more strongly foUated. So far as could be perceived, the foliation is in all 
cases due to, or at least associated with, fault-movement. The t\'pical serpentine-schist 
of Serpentine Creek (Upper Hokitika) is a handsome, translucent, dark-green rock, which 
often appears beautifully poUshed along the foliation-planes.f It is, however, too shattered 



* SoUais and McKay : " Rocks of Cape Colville Peninsula," vol. ii, 1906, p. 193. 
I See note at end of this chapter. 



PLATE XXIV. 






MlCIiO-I'HOTOGHAPHS BY Dli. P. MARSHALL. 

1. Serpeiitinedunite, Mount Bowen. Antigoritic serpentine (light) is developing in olivine (dark- 

coloured). 

2. Grain of chromite-magnetite embedded in antigoritic serpentine. The small black spots are mag- 

netite. 

3. Arenaceous foraminiferal limestone, Smyth Creek. The angular grains towards the left and bottom 

are quartz. 

All magnified about 30 diameters. 



Gtol. Bull. Xo. 6.] 



[To fare page 12i. 



Pl.ATK XXV 







^^^^^^^^ 




/ 



View of Mouxt 0"Coxxoh (."),9.j( ft.) fkom ^Fouxt Ixframeta, showing Falls ix Sekpextixe 
Creek. The Valley below is that of the Hokitika River. 




Mouxt Ixfkameta (4,482 ft.) from Wiiitcombe Valley. 



Gtol. Bull. Xo. 6.] 



[To fore jiogc US. 



123 

to be of use as an ornamental rock. The serpentine-schists are accompanied by much the 
same minerals as the ordinary serpentines. 

(4.) Talc-ser'pentine and Talc-rock.— Some of the serpentines contain a good deal of talc 
in a form not recognisable in the hand-specimen on account of its hardness being about equal 
to that of the serpentine. A full petrological description and analysis of such a serpentine 
from Mount Junibletop is given in the next section. In many places the original ultra-basic has 
been so completely metamorphosed that it appears as a rock with talc as its principal mineral. 
The colour of these highly altered rocks varies from a brownish-red to almost white, according 
to the quantity of iron which has been leached out. The colour is also to some extent an index 
to the amount of serpentine present. Besides serpentine, the other minerals formmg these 
talcose rocks are dolomite, or magnesite. calcite, quartz, actmolite, iron-oxides, pyrite, &c. 
Talc rocks occur at the Whakarira Gorge (Kokatahi Rjver), and form long bands near Mount 
Jumbletop, and on the slopes of Mount Bowen, west of the two serpentine-dunite belts. 

Ill the bed of Macmillan Creek a narrow band of soft talc-actinolite rock was seen 
enclosed in talc-schist, and boulders of similar rock were observed in other parts of the 
Toaroha Valley.* 

(5.) Miscellaneous Rocks. — A number of rock specimens, with peculiar characters have 
been obtained froni time to time, which, though not found actually in situ, may with more or 
less confidence be referred to the Pounamu Formation. Among these may be mentioned 
actinolite-epidote rock, tremolite-quartz rock, so called ruby rock or • goodletite," and the 
remarkable rock specially described on pages 127 and 128. 

Actinolite-epidote rocks are common as loose boulders in the valleys of the Hokitika and 
Whitcombe rivers, and by rea,son of their unusual appearance are easily recognised. The 
hand-specimens are handsome rocks, showing dark-green actinolite embedded in epidote of 
characteristic yellow-green colour, with a little magnetite, pyrite, &c. Under the microscope 
the epidote is seen to occur both as rounded grains and as fairly well-developed crystals, with 
the usual extremely strong double refraction. The actinolite is in long, green prisms with 
moderate pleochroism. Besides pyrite and magnetite a little quartz may be present. In a 
ligl^t-coloured specimen from the valley of Serpentine Creek, a tributary of the Upper Hokitika, 
the microscope showetl that quartz predominated. Epidote was in rounded grains, and 
actinolite occurred as in the last variety. A Uttle feldspar and mica were also pre- 
sent. 

Though not discovered actually (« situ, actinolite-epidote rocks were found in the valley 
of Sei-pentine Creek, and near the top of Mount Inframeta, in such positions that it was evident 
the specimens had come from outcrops in the neighbourhood. In both cases exposures of 
serpentine were close at hand, and it therefore seems certain that the actinolite-epidote rocks 
are connected with the Pounamu Formation. An analysis made of a specimen containing 
some pyrite showed that copper, chromium, and manganese were present ; but gold, silver, 
and platinum were absent. 

Tremolite-quartz rocks occur in the valley of the Toaroha, but have not been located 
in situ. Loose boulders are fairly numerous in the bed of the lower part of the river. They 
consist mainly of quartz, with rather striking radiating crystals of light-coloured or brownish 
tremolite, and generally some pyrite. Rhodonite is occasionally present, together with some 
manganese-oxide. The connection of the boulders described with the Povmamu Formation 
is a conjectural one, but they can hardly come from anywhere else than its neighbourhood. 

The ruby rock, or "goodletite," has hitherto been found only in the form of loose boulders 
in the gold-bearing drifts of Rimu, Kanieri, and Kanieri Forks, and in the Whitcombe 
Vallev. 



* A specimen from one of these boulders haa been described by Professor Bonney. See note at end of 
this chapter. 



1-24 

It is composed of a matrix of a beautiful green colour, whicli lias not yet been certainly 
identified,* in whicli are embedded numerous small dark-red rubies, which contrast well with the 
green matrix. Though most of the rubies are not transparent enough to be called gem stones, 
a few show promise of being valuable to the jeweller. 

Since there has been some discussion as to whom the credit of discovering the nature of 
the ruby rock belongs, a statement of the facts may be here inserted. 

McKay states that a sample of the now well-known ruby rock obtained by him in Decem- 
ber, 1891, was shortly after submitted to the late jVIr. William Skey, formerly Colonial Analyst, 
and pronounced by him to contain rubies. This result, however, owing to an oversight, was 
not recorded or pubUshed at the time.f Previously to this corundum or emery had been 
identified in the Rimu School of Mines as occurring in the Rimu gold- drifts. J Some time 
later specimens taken to Dunedin by Mr. William Goodlett were tested by the late Professor 
Ukich, and found by him to contain oriental rubies of fine colour. 

Since 1892 many unsuccessful attempts have been made to discover the ruby-bearing 
rock in situ. It was concluded that the ruby rock must have come from the watershed of the 
Hokitika, whence are derived most of the boulders in the Rimu drifts, and search was con- 
sequently made in that direction. The discovery said to have been made by one prospecting 
party of boulders of the rock in the Whitcombe Valley seems to localise the place of origin still 
further. 

McKay considers that the ruby rock is associated with the serpentine (Pounamu) forma- 
tion, and this opinion is very generally accepted. 

During the season of 1906-7 the very careful examination of the Pounamu Formation made 
by the Geological Survey party failed to reveal any ruby-bearing rock, nor were any signs of it 
detected elsewhere. Thorough search of the Whitcombe and Cropp river -gravels, with 
repeated pamiing-tests, was also unsuccessful in bringing any samples of ruby or of the 
characteristic ruby rock to light. It may therefore be regarded as very rare. 

Finally, reference must be made to a very peculiar metamorphosed rock, of which numerous 
large boulders are found in the Whitcombe River bed below the Cropp River junction. Some 
of the boulders apparently belong to a banded igneous rock mth large porphyritic feldspars, 
but others show a transition to a fine-grained schist. The sections made show under the 
microscope a tricUnic feldspar, quartz, biotite, tremolite, green hornblende, zoisite, some 
cloudy material, and a considerable amount of serpentine. 

No exposure of this rock could be discovered either in connection with the serpentine 
sills of the district or in the neighbourhood of the serpentine-dunite of Mount Bowen, and 
it is therefore supposed that it outcrops in the inaccessible gorge of the Cropp River. 

Special Petrology. 
1. From talc-serpentine outcrop a quarter of a mile east of Jumbletop. 

The hand-specimen is a dark-green semi-translucent rock, containing a brown weathering 
carbonate, which does not effervesce with cold dilute hydrochloric acid, and is probably 
ferriferous magnesite. The rock has a uniform hardness of about 2*5 to 3, and therefore the 
talc present must be harder than typical talc. On the joint-surfaces, which are also move- 
ment planes, there are thin flakes of a fairly hard, transparent, green substance, which may 
be called bowenite (tangiwai of Maoris). 

Under the microscope the principal minerals are serpentine and talc in nearly equal 
quantity, the latter perhaps predominating. A carbonate (probably magnesite, since analysis 
shows absence of lime) forms several small patches along a vein of serpentine. A brown 

* It is allied to the micas, and has been regarded as margarite (Professor G. H. F. Ulrich) or as fuchsite. 
An analysis made of some moderately pure material shows that chromium is present. The silica percentage, 
however, is too low for a pure fuchsite, but is consistent with a mixture of fuchsite and margarite. 

t '" Geological Explorations of the Northern Part of Westland," Mines Report, 1893, C.-3, p. 151. 

} Loc. cit., p. lol. 



126 



oxide of iron, magnetite, and possibly a very little chromite or picotite are also present. No 
original olivine could be detected. 

The serpentine is in patches of various sizes, which are surrounded by talc, and show under 
crossed nicols a kind of mosaic structure with extremely low polarisation colours. It is also 
in small veins crossing the section. Mesh structure is very evident in some parts, and deriva- 
tion from oli\^ne is also clearly suggested by the rather regular arrangement of the opaque 
impurities in small patches, and in curving bands which evidently mark the original crystal 
selvages. 

Talc, in rather wide bands, forms meshes round the serpentine and the borders of the 
original crystals, some of which are entirely converted into talc. It is very interesting to 
note that conversion into talc has probably followed the same lines as the original ser- 
pentinization. The talc shows extinction parallel or nearly so to the bands. The interference 
colours are bright, sometimes reaching blue and green of the second order, but are on the 
whole not quite so high as those to be expected from typical talc. 

The presence of talc in the serpentine rock is confirmed by the following analysis, which 
shows a relatively high percentage of silica as compared with magnesia :— 

Silica (SiOa) .. 

Alumina (AUOj) 
Ferric oxide (FeaOg) 
Ferrous oxide (FeO) . . 
Manganous oxide (MnO) 
Lime (CaO) 
Magnesia (MgO) 
Alkalies (NajO and KoO) 
Chromic oxide {Cr203) 
Titanium-oxide (TiOj) 
Carbonic anhydride (COj) 
Water and organic matter 







2-84 






2-56 






447 






0-25 






. Nil. 






. 34.38 






0-20 






0-30 






Nil. 






0-74 






8-77 



100-27 

2. From serpentine boulder in Cropp River. 

The hand-specimen is a handsome rock, consisting largely of light-green, somewhat 
translucent serpentine, with a tendency to a radiately fibrous structure, and subpearly lustre. 
There are many darker patches, which indicate a transition to the original dunite or perido- 
tite. Portions of the specimen show a poorly developed autigoritic lamination. 

The section consists almost entirely of the light-green serpentine, and under the micro- 
scope lath structure is seen to predominate. There is also a very small amount of residual 
augite, together with a single irregular crystal of poorly pleochroic Ught-green amphibole, 
a little magnetite, one or two small grains of pyrite, and residual impurities of a brown colour 
arranged in small, often irregular patches. A few minute fragments of possible olivine are 
present. 

Where dust-patches occur, the lath structure is absent and the birefringence very feeble. 
In the laths the polarisation colours range to the nearly pure white of the first order. They 
may therefore be considered as antigorite.* 

3, 4, 5, and 6. Serpentine-dunite from the large outcrop near camp on south-east slopes of 

Mount Bowen. 
Tha specimens were selected at intervals from the south-east edge of the outcrop towards 
the centre. The general macroscopic and microscopic description given under the heading 
of serpentine-dunite applies to these samples. (See also Plate XXIV, Nos. 1 and 2.) 



See note at end erf this chapter. 



126 

The distribution of chromite in these sections is noticeably local and erratic. 

No. 3 has one large grain of chromite-magnetite, whilst No. 4 has no chromite, No. 5 has 
numerous grains of chromite-magnetite arranged in two patches, and No. 6 has two grains in 
close proximity. 

The following is an analysis of No. 4 : — 



Alumina (AI2O3) 






2-24 


Ferric oxide (FejOa) 






304 


Ferrous oxide ( FeO) . . 






4-90 


Manganous oxide (MnO) 






0-28 


Lime (CaO) 






Nil. 


Magnesia (MgO) 






. . 44-28 


Alkalies (KgO and NagO) 






0-20 


Chromic oxide (Cr203) 






0-28 


Titanium-oxide (TiO^) 






NU. 


Carbonic anhydride (CO 3) 






0-60 


Water and organic matter 






5-68 



100-32 



7. Serpentine from near Noisy Creek (south-west slopes of Mount Bowen). 



The hand-specimen is a dark-green semi-translucent rock, almost homogeneous in grain. 

Under the microscope the section consists of serpentine, magnetite, a little haematite, 
and some talc. 

The serpentine is either in well-marked antigoritic la,ths, showing under crossed nicols 
polarisation colours up to almost pure white, or in patches with indistinct mosaic structure and 
very feeble double refraction. These patches are coloured brownish by a fine dust, while the 
laths are quite clear. The magnetite is in extremely irregular masses, which are deeply cut 
by narrow serpentine-filled channels, and are almost entirely confined to one part of the sec- 
tion. Talc is not abundant. It occurs in small irregular veins, and in only one part of the 
section does it form a patch of any size. Chromite cannot be detected, but the magnetite 
may perhaps be chromiferous. 

8, From segregation in serpentine-dunite of Mount Bowen. 

The hand-specimen is a white substance with a peculiar fibrous or flow structure. In 
part it is passing into asbestos. A crystal or two of pyrite is present. 

Under the microscope the section shows a banded structure, the bands being alternately 
colourless and, partly from included dust, brownish. The latter bands show rather slight 
but yet well-marked pleochroism. 

The central parts of the brown bands extinguish under crossed nicols at an angle of from 
0° to 18° with the longitudinal direction ; the outer parts extinguish at 20°. Some of the 
colourless matter is nearly isotropic, and may be serpentine ; the rest extinguishes at angles 
of from 0° to 20°. 

The conclusion that tremolite forms almost the whole of the specimen is supported by 
the following analysis, beside which are placed an analysis of a Swedish tremolite quoted 
from Dana's " System of Mineralogy " (page 390), and also the theoretical percentages of 
a pure tremolite with the formula CaMgjSi^Ojj : — 



127 





1. 


2. 


3. 


Silica {Si02) 


. . 58-23 


57-62 


57-7 


Alumina (AljOg) . . 


106 






Ferric oxide (FeaOj) 


Nil. 






Ferrous oxide (FeO) 


2-28 


0-84 




Manganous oxide (MnO) 


047 






Lime (CaO) 


1040 


14-90 


134 


Magnesia (MgO) . . 


. . 24-91 


2612 


28-9 


Potash and soda (KjO and Na^O) . 


0-45 






Chromic oxide (Cr^Oa) 


Nil. 






Carbonic anhydride (COj) . . 


003 






Water and undetermined . . 


2-17 




•- 



100-00 9948 1000 

1. TremoUtic mineral, Mount Bowen. 

2. Tremolite from Gulsjo, Wermland. 

3. Theoretical tremolite. 

9. From loose boulder in Serpentine Creek, Upper Hokitika. 

The hand-specimen is a tough, close-grained, light-yellow rock, mth radiating tufts of 
actinolite. The needles of each tuft spread out in one plane, and help to give the specimen 
a slightly banded appearance. A little pyrite is present. 

Under the microscope the section is seen to consist of epidote, quartz, actinolite, feld- 
spar, and biotite. 

Epidote, the most abundant mineral, is developed as pale-yellow, slightly pleo- 
chroic grains, masses, and well-shaped crystals with monoclinic symmetry. Cleavage is 
often well exhibited, and the mineral presents the usual high polarisation colours. 

Quartz forms most of the remaining part of the section, and appears in mosaics of rather 
small irregular grains, with somewhat erratic extinction, probably due principally to over- 
lapping. 

Actinolite is not so plentiful in the slice as in most parts of the hand-specimen. It 
is in well-formed needles, showing bluish-green to light-green and light-yellow pleochroism. 

There are two nests of fresh feldspar grains in the section. These are remarkably clear 
and quartz-like, but some individuals show binary twinning, and even apparent traces 
of repeated twinning, as well as a poorly developed cross -cleavage. The extinction -angles 
observed range from 0° to 23°, and on the whole the feldspar is, perhaps, to be regarded as 
valencianite. rather than any of the plagioclases. 

A httle brown biotite, associated with the actinolite, is seen in the section. 

10. Loose boulder from Whitcombe River bed, below Cropp River junction. 

The hand-specimen is a light-coloured rock with dark spots, which by its appearance 
suggests a possible igneous origin. 

The section is seen under the microscope to consist of tremolite or other amphibole, biotite, 
feldspar; serpentine, cloudy material and numerous little prisms of an undetermined mineral 
which is probably zoisite. 

The tremolite is mainly in large patches with ragged outlines and a strong tendency to 
fibrous structure. It is non-pleochroic, and colourless, with an extinction-angle of 18° to 20°. 
Some of the patches are more or less converted into serpentine. There are also many small 
individuals in the groundmass. These are generally serpentinized. 



128 

The biotite is also in large ragged patches. It has good pleochioism and vivid polarisation 
colours. It occasionally partly encloses serpentine laths. 

Feldspar is rare and in small prisms, which are usually badly defined. One example shows 
twinning. 

Besides the altered tremolite, many small clear patches which polarise in feeble colours 
may also be referred to serpentine. 

11 and 12. From a loose boulder in the Hokitika River bed, below the Whitcombe junction. 

The hand-specimens show that the rock is of two distinct types. One is a rock with 
white groundmass, plentifully spotted with dark patches, and ha\dng a very slightly de- 
veloped schistosity ; the other is a luiiform tough grey rock with fairly well-developed banding. 
The two types meet along an irregular surface in such a way as to show that they represent one 
and the same rock-mass. 

Under the microscope the following minerals are seen to be present : Amphibole of more 
than one species (including possible uralite), biotite, feldspar, quartz, serpentine, epidote, 
kaolinitic matter. 

Amphibole is present in large fibrous patches with a tendency to serpentinization. These 
are almost non-pleochroic, but polarise in bright colours. Some patches show the character- 
istic cross-cleavage ; these are noticeably pleoehroic (light-brown to pale-yellow). There are 
also several laths of strongly pleoehroic hornblende (bright-green to bluish-green to yellow) 
with vivid polarisation colours. In one place some of this green hornblende forms the well- 
defined end of a large crystal, the greater part of which is fibrous material (partly serpen- 
tinized). 

Biotite occurs in large irregular plates with strong pleochroism. but is partly bleached 
and otherwise altered. 

Feldspar is rare in the sections. 

Serpentine is present much as in section No. 10. 

One of the sections shows the passage from the coarse-grained rock to the fine-grained 
grey type. This latter part is seen to consist mainly of a mosaic of epidote and qiartz 
arranged in parallel bands and veins, with some serpentine (probably), kaolinitic matter, &c. 

Remarks. — The peculiar type represented by specimens Nos. 10, 11, and 12 was originally 
a basic igneous rock which became partly serpentinized by the introduction of water. It then 
seems to have been subjected to the influences of heated siliccoi s solutions, which partly 
broke down the rock, causing the formation of the fine-grained mosaic of epidote and quartz. 
This process was accompanied by sufficient diiTerential pressure to cause a banding of the newly 
formed or forming epidote and quartz. 

Metamorphic Influence. 

The metamorphic influence of the Pounamu Formation has been due not so much to the 
ultra-basic rocks themselves as to the hydrothermal solutions which accompanied or followed 
them. At the time when the igneous intrusions took place the enclosing rocks of the Arahura 
Series were almost certainly deeply buried, and at a fairly high temperature, which was 
perhaps not much increased by the comparatively small sills of the formation. It was the 
period, too, when mountain-building was in progress and folding still taking place. 

The belt of the middle schists which encloses the various outcrops of the Pounamu For- 
mation, as observed on page 84, is. generally decidedly more metamorphosed than the rocks 
on either side. Here, silicification is very evident along certain bands, whilst along others, 
usually more narrow, talc is developed to a great extent. Near and adjoining the ultra-basic 
rocks themselves the bands of talc-schist, as described in Chapter VI, are very wide. The 
ultra-basics themselves have been largely converted into serpentine and even talc by the 
hydrothermal solutions, whilst actinolite, tremolite, epidote, pyrite, magnetite, quartz, and 



12P 

other minerals appear in quantitv. That pyrite. for example, was formed at this time and not 
later is shown by its frequent occurrence in distorted or flattened cubes of exceptional hard 
ness, which presumably must owe these features to pressure during the mountain-building 
period. 

NoTB. — As this bulletin is going through the press, an important paper by Professor T. G. Bonney, 
entitled "On Antigorite and Aiitigorite-.Serpentines" (Q.,T.(!.S., vol. Ixiv. 1908. pp. 152-170). comes to 
hand. In this paper (pp. 158-161) descriptions of several ultra-basic rocks from the Mikonui Subdivision 
are given. Specimen Xo. 2, briefly described on i)agc 125 of this bulletin, is from the same iocahty as the 
antigorite-serpentine described near top of page 160 of Professor Bonney's |)aper (Cross River is a misprint 
for ("rop]> River). The serpentine of .Asbestus for Serpentine] Creek (p. Uil. Bonney) is referred to on 
page^ 121 and 122 of this report. 

It may be added that lamination or foliation is not characteristic of the Westland antigorite, .ind that 
there can be no doubt that some (if not nearly all) of it is derived from olivine. See general description of 
aerpentine-dunite on page 121. Reference may also be made to Bull. No. 1 (New Series), X.Z.G.S., p. 69. &c. 



y -Mikonui 



130 



CHAPTER XII. 



THE TUHUA OR GRANITE FORMATION. 



Paae > Paee 

Content . . . . . . . . 130 Distribution . , . . . . 131 

Mode of Occurrence . . . . . . 130 General Petrology . . . . . . 132 

Origin . . . . . . . . 131 Special Petrology . . . . . . 133 

Age and Correlation . . . . . . 131 Metamorphic Effects . . . . 136 

Content. 

The rocks included under the heading of Tuhua Formation are, in the Mikonui Subdivision, 
acid plutonic rocks of somewhat uncertain age, which consist mainly of biotite-gramtes or 
granitites. A few aplitic dykes and an occasional band of pegmatite proceed from the main 
bodies into the surrounding rocks, but pegmatitic or aplitic dykes within the granitic bosses 
themselves are very rare, if not altogether absent. 

In the Hokitika Bulletin the Tuhua Formation included certain giieissic rocks which 
in the Hokitika Subdivision were more or less doubtfully involved with the plutonic rocks. 
The much greater development of similar rocks in the Mikonui area has led to their being 
entirely separated in this bulletin from the Tuhua Formation, and for the various reasons 
detailed in Chapter VI they have provisionally been constituted a subdivision of the Arahura 
Series. 

Mode of Occurrence. 

The Tuhua rocks form great bosses which have been forced into the lowest division of the 
Arahura Series, the gneissic schists, and into the Greenland rocks. The accompanying maps 
show six of these bosses, besides two minor outcrops, one of which occurs some miles from 
the nearest of the larger masses, and west of the general line. Some of the bosses arc separated 
on the surface only by narrow bands of other rocks, and there can be no doubt but that in 
depth they are continuous. 

There are good reasons for thinking that the intrusion of these plutonic masses is connected 
in some way with the mountain-building process which has formed the Southern Alps. All 
the mail! outcrops occur along or close to the great thrust-plane which separates the Arahura 
Series from the Greenland rocks. They may be regarded, to use one of Suess's phrases, as 
cicatrices marking the healing of a wound in the earth's crust. The sharp contacts with rocks 
of the Greenland Series, and the fewaiess of imdoubtcd dykes connected with the formation, 
lead one to think that the granite bosses at the time of injection were in a semi-fluid or all but 
solid condition, at least towards the final stages of the intrusions. It seems probable also 
that " stoping " or wholesale swallowing-up of the overlying rocks, such as is suggested by 
R. A. Daly as accompanying great igneous intrusions,* did not take place to any great extent. 
Numerous inclusions of gneissic schistf and grauwacke were observed, in many cases of small 
size, but decidedly angtilar, so that while the plutonic rocks must have been sufficiently plastic 
to be moulded round these fragments, they were not able to attack them to any great extent. 
Such a condition implies also the absence of superheated aqueous solutions, or, at least, that such 
solutions were not prevalent within the mass of the intrusions. This inference is confirmed 

* " Mechanics of Igneous Intrusion," Am. Journ. Sci. 1903, xv (4). Reference quoted from E. C. 
Andrews in " The Geology^of the New England Plateau," Records Geol. Survey of New South Wales, 
vol. viii. Dt. ii. 1905, p. 120. 

t Often different in appearance from the gneissic rocks at the base of the Arahura Series. 



181 

as regards the Mikonui Subdivision by the almost entire lack of pegmatite dykes, the 
scarcity of grcisen and aplite veins, and the paucity of evidence for hydrothcrmal action in 
the intruded rocks of the Greenland Series. On the other hand, it must be borne in mind, 
as suggested by Andrews, that in cases like this we see the dying struggles of a great intrusion, 
and not its vigorous youthful efforts.* In the Hokitika Subdivision there is far more CAn- 
dence of aqueo-igneous action than in the area being discussed. t Moreover, the effects produced 
on the rocks of the Greenland Series, as described on page 137, prove that the plutonic rocks, 
even if not very fluid, were, comparatively speaking, extremely hot at the time of their irruption 
into the sedimentary rocks, and were able, during their slow cooling, to effect considerable 
thermal metamorphism. Most signi^fcant of all, however, are the changes produced in the 
gneissic schists, though in their case, owing to other factors, it is impossible exactlv to state 
the extent of the thermal metamorphism brought about by the granitic intrusions. 

Origin. 

It was suggested in the Hokitika Bulletin that the "Westland granitesj may be the re-fused 
equivalents of the rocks composing the very ancient land which by its decay gave rise to the 
sediments of the Axahura and Kanieri (Greenland) Scries.§ There is nothing visible in tlie 
Mikonui Subdi\-i«i'm which controverts this view ; but for the'prpsent the plutonic rocks may 
be regarded as extrusions from an acidic magma of unknown origin, and probably of great 
dimensions. 

Age and Correlation. 

Judging from Cox's classification of 1877, it would seem that this writer regarded the 
granites as possibly of greater age than any of the schistose or sedimentary rocks; but he 
also distinctly states that they are of intrusive character— at least, in places.]] Von Haast 
groups th(-m with the gneissic rocks, and regards the whole series as older than the mica-schists.^ 
McKay, though aware that the granitf-s were intrusive into the older sedimcutarits,** nowhere 
in his reports makes any very definite statement of age. Hutton considered the Westland 
granites to be of Permian ageft ; but this view, the \mter believes, was based on a correlation 
with certain granit.-s in Nelson, and not on actual examination. Certainly there are, or have 
been, pre-Triassic granites exposed in Nelson, for the fossiliferous conglomerate at Eighty- 
eight Valley, not far from the Town of Nelson, contains pebbles of granite. Again, at Chasm 
Creek, in the Mokihinui ilistrict, the coal-measures rest on a denuded surface of granite, which 
may well be of great age. On the whole, it seems most probable that the granite intrusions 
are synchronous with the earlier of the orogenic movements which produced the Southern 
Alps, and therefore, it is likely, of Eocene age. 

Distribution. 
The general distribution of the Tuhua rocks has already been indicated in the statement 
that they lie along or on the western side of the great thrust-fault separating the alpine ranges 
from the lowlands and the area occupied by Greenland rocks. The mo st northerly of the 

* "The GeologyTof the New England Plateau." Records Geol. Survey of New South Wales, vol. viii. 

pt. ii., 1905, p. 126. 

+ Bull. No. 1 (New Series). N.Z.G.S., 1906, pp. 21, 61. .,,„■.■ * _„.,ifi„ 

i Here and el.sewhere in this chapter granite is used as a field name to include all varieties of granitic 

rocks The writer finds the old usage of the term far too convenient to be lightly abandoned. 

^^iSoli^^lSlsS^'-C^^-'uring 1874-7^ v.l.i. 1877.. 72. On , ^ ^e s-^ 
that the metamorphic rocks and the older fossiliferous beds (at Reefton) are probably of greater age than 

^" ^".?GeoS" of Canterbury and Westland," 1879, pp. 242, 251, 252. On p. 253, however, he speaks of 
granite dykes penetrating the metamorphic rocks. , „, ,, . .. p o .oqi n 17? 

^ * "Geological Explorations of the .\orthern Part of Westland, .. C--3, 1893, p. 173^ associates 

tt " The Geological History of Xew Zealand." Trans., vol. xxx.i, 1899. p. 167. Hutton here associates 
i,he granites jWith a folding^period. 
9'— Mikonui. 



132 

bosses is probably ou the liiie ot tault, and composes the whole of Doughboy Hill, which, 
rising to a height of 1,967 ft., forms a prominent isolated elevation near the eastern margin 
of the Koiterangi-Kokatahi Plain. 

To the south, the next mass of Tuhua rock is that which outcrops at the Hokitika Gorge, 
and forms most of the higher part of Mount Misery. It is to a great extent surrounded by 
gneissic schist, and is just on the east side of the great fault-line. Extending northward 
from the neighbourhood of Mount Misery is the long, somewhat narrow mass of granite 
which forms Doctor Hill and some lower elevations. 

South-west from Mount Misery another long boss extends to Bald Hill Range. Parallel 
to this, but much shorter, is a smaller mass forming part of Fraser Peak. This is separated 
from the Bald Hill boss only by a narrow band of gneissic schist, and without much doubt 
joins it a few hundred feet below the surface. 

South of the Mikoniii there begins by far the largest boss in the subdivision. The out- 
crop forms most of the south-east flank of Mount Rangitoto, and, extending across the summit 
of the mountain as a narrow band, widens out again on the western flank. It also extends over 
much of the broad saddle south of the mountain. Crossing the Kakapotahi it extends as a 
wide band to the valley of the Waitaha, where it suddenly ceases, apparently against a fault- 
plane. 

There is a small outcrop of aplitic granite in the lower valley of Shearer Creek, which 
extends in a north-west direction for about half a mile, where it may be seen outcropping along 
the McLeod's Terrace Sluicing Company's water-race. The rock consists principally of quartz 
and feldspar, with but little mica. 

Finally, in the upper valley of Duffer Creek, which descends from Mount Bonar, there 
is a band or patch of rock enclosed in gneissic schists which must be pronounced as certainly 
granite. It may be seen on the east side of the creek about a mile and a quarter above the 
road-crossitig. The outcrop exhibits a grey rock composed of feldspar, quartz, and chloritic 
biotite. 

Judging by the boulders seen in Duffer Creek, there may be another exposure of granite 
in its valley, but none was found. Elsewhere there is almost certainly no true granite out- 
cropping on the slopes of MoTint Bonar, but it seems probable that a mass of granite forms 
the core of the mountain. The presence of rather abundant tourmaline in some of the rocks 
on the east side of the mountain and the hiph degree of metamorphism of the exposed 
gneisses are in favour of this view. 

General Petrology. 

Macroscopically the granites of the Mikonui area exhibit two distinct tj^es, one with 
large porphyritic crystals of orthoclase, and the other with the accepted granitic structure. 
The porphyritic type is well developed at Doughboy Hill, and to a limited extent at the Hoki- 
tika Gorge. In the former locality the orthoclases are arranged with their long axes in a 
vertical position, thus giving the rock a decided flow appearance. These large crystals 
invariably contain more or less quartz as a graphic intergrowth. 

Usually the granites are of a grey colour, but at Falls Creek they have in general a 
slight pinkish tinge, due to abundant development of pale-pink feldspar. At Humbug Creek, 
at the head of Bevan Creek, and elsewhere they have a decided red tint, owing to incipient 
decomposition having liberated oxide of iron. 

As a rule the granites are biotite-granites, or granitites, muscovite being seldom 
developed, and, when present, seemingly of secondary origin. Hornblende - biotite - granites 
(hornblende -granitites) are also present, together with aplite and pegmatite dykes (the last 
very rare), but there arc apparently no muscovite-granites, or biotite-muscovite-granites (true 
granites of some authors), although these are represented to the north of the subdivision. 



133 

Biotite-gr unites. — The feldspars present consist of orthoclase, microclme, albite, and oligo- 
clase, with possibly occasionally more basic plagioclases. The orthoclase, and to a less extent 
the albite and oUgoclase are generally markedly decomposed. The microcUne in the one type 
of microcline-granite examined was beautifully fresh. Quartz appears as interlocking grains, 
often with strain extinction, and in graphic intergrowths with feldspar. Biotite is frequently 
less plentiful than in typical granites. It sometimes exhibits particularly fine pleochroism, 
and not seldom contains sagenitic webs of rutile. 

The other original minerals present include magnetite (probably often titaniferous), 
apatite, and zircon. The secondary minerals present are hornblende or other amphibole, 
sericitic muscovite, epidote, chlorite, and pyrite. 

Hornblende-biotite-granites. — These differ from the last type principally in the presence 
of abundant hornblende, but there were several other points of difference in the one specimen 
microscopically examined. Macroscopically they are rather coarse-grained, and are darker 
than the biotite-granites. 

Aplite. — Aphte dvkes penetrating Greenland rocks were observed in Doctor Creek near 
the granite gorge, in Humbug Creek, and in the bed of Anderson Creek near the Waitaha 
Sugarloaf. The aplite dvkes in these localities vary from a few inches to 2 ft. or 3 ft. in 
thickness, and are light -coloured, or of a pale-red tint, due to liberation of iron-oxide. The 
microscopic examination of one of these dykes showed that it consisted largely of a feldspar 
approaching albite-oligoclase. 

Dykes of aplitic character were also observed penetrating gneissic schist — one at the 
head of Humbug Creek, and two in Duffer Creek. The one in Upper Humbug Creek was 
about 6 ft. thick ; those in Dufier Creek were 9 ft. and 15 ft. in thickness. These dykes con- 
sisted of rather coarse feldspar and quartz, with a little muscovite, thus exhibiting an approach 
to pegmatite. 

Pegmatite.— A large pegmatitic dyke was observed in the bed of Anderson Creek, a 
little to the north of the Waitaha Sugarloaf. In this case the enclosing rock could not be 
observed, but it is probably grauwacke of the Greenland Series. The outcrop, which is about 
15 yards wide, shows a very coarse-grained mixture of 'quartz and feldspar, with scattered 
nests of muscovite plates, reaching 1 in. or perhaps more in length and width. Tourmaline is 
present in coarse, poorly developed crystals, which occur in patches. 



Special Petrology. 

1. From Hokitika River Gorge. 

The hand-specimen is a fine-grained grey rock with holocrystallme structure. Quartz, 
feldspar, and biotite seem to be present. 

Under the microscope the following minerals appear in the section : Orthoclase, albite 
and perhaps other plagioclases. biotite. quartz, hornblende, apatite, zircon, sagenite (rutile), 
magnetite, epidote. The structure is t>T)ically granitic. 

Orthoclase is not verv abundant, the bulk of the feldspar being albite, with perhaps other 
acid plagioclases. Biotite is ver>- plentiful, and often contains fine needles of rutile (sagemte), 
crossing at angles of about 60°. 

Quartz is present m fair quantity, m shapeless masses with very irregular outhnes. 

Hornblende is seen only as small laths enclosed m other minerals. It is probably a 
secondarv' product. 

Oneor two rather large apatite cr>-stals occur, together with numerous small zircons, some 
magnetite, and a very Uttle epidote. 

The rock is a biotite-granite (granitite). 



134 

2. From Holdtika River Gorge. 

The hand-specimen is a moderately coarse-grained rather dark rock, with white spots 
and bands. Biotite is well developed along decided planes of schistosity. 

Under the microscope the following minerals appear in <the section ; Plagioclase, biotite, 
muscovite, hornblende, quartz, magnetite, zircon, epidote, and pyrite. Schistosity is not very 
evident, and the structure appears granitic. 

The plagioclase is probably partly basic oligoclase, partly other Ume-soda feldspar 
ranging towards acid labradorite. It shows good twinning, and is often saussuritized to some 
extent. 

Biotite is plentiful, and shows extremely fine pleochroism, ranging from a dark-brown 
through a somewhat violet or purple tint to nearly colourless. 

Hornblende is also plentiful. It shows good cross-cleavage and exhibits fair pleochroism 
(brown to light-green to very light-yellow). 

Quartz occurs in much the same way as in No. 1. The extinction is often somewhat 
irregular. 

There is very little magnetite present, most of the original mineral ha^ang been replaced 
by pvrite. 

Remarks. — The rock may be called hornblende-biotite-granite (hornblende-granitite). 
With its schistose appearance, abundant hornblende, and feldspar in part of rather basic 
character, it approaches some of the rocks described in the gneissic series. It is included in 
the granites on account of its structure, and its field relations so far as these could be made 
oTit. Nevertheless, it is by no means impossible that it actually belongs to the gneissic 
series. 

3. From Flat Creek, Mount Eangitoto. 

The hand-specimen is a characteristic hght -coloured granitic rock, with abundant feldspar 
and quartz, but not much mica. 

Under the microscope it is seen to consist of feldspar, quartz, biotite, muscovite in the 
form of secondary sericite, magnetite, apatite, epidote, and chlorite. The structure is typically 
granitic. 

Feldspar, the most abundant mineral, is largely in the form of microcUne. Some of the 
grains, apparently orthoclase, include irregular or vomided patches of a feldspar with higher 
polarisation colours which is probably a Iime-soda'^(plagioclase. Other individuals which 
show faint repeated twinnmg bands are ahnost certainly albite. The microcline is fresh, 
but the supposed orthoclase is highly altered, some i portions consisting almost wholly of a 
patchwork of sericite. Epidote, kaoUnitic matter, and 'quartz are also other alteration- 
products seen more especially along the edges of the orthoclase grains. 

Quartz is plentiful, and commonly shows strain extinction. Some is intergrown with 
feldspar in graphic form. The larger grains are often bordered with a ring of smaller grains. 

Biotite in ragged chloritized flakes is not very abundant. The greater part of one flake 
has been converted into epidote. 

Apatite is represented by one or two small crystals. 

Magnetite is very rare, and represented only by small grains or crystals. 

Chlorite and epidote are fairly common throughout the section. 

Remarks. — The rock is a biotite-granite or granitite. The freshness of the microcline 
and its relations to the orthoclastic feldspar and the albite suggest, but do not prove, that 
it is^of later origin, and belongs to a secondary crystaUization. There is nothing to indicate 
that it has been derived from orthoclase by means of pressure. An analysis of the rock is 
appended : — 



135 



Silica (SiOj).. 

Alumina (Al^Og) 

Ferric oxide (FcaOg) 

Ferrous oxide (FeO) . . 

Manganoufl oxide (MnO) 

Lime (CaO) . . 

Magnesia (MgO) 

Potash (KjO) 

Soda (NajO) 

Phosphoric oxide (P2O-) 

Titanium-oxide (TiO,) 

Carbonic anhydride (COj) 

Loss on ignition (excluding COg) 



72-72 
12-76 
Nil. 
3-45 
0-25 
1-23 
0-10 
4-75 
2-89 
0-22 
0-25 
009 
101 



99-72 

To the descriptions given above may be appended two of grauwacke fragments enclosed 
in granitic rocks. 

4. Supposed grauwacke inclusion in granite, Holdtika Gorge. 

The hand -specimen is a grey indurated rock from an inclusion about 6 ft. long by 1 ft. 
thick. 

Under the microscope the section is seen to consist of quartz, biotite, feldspar, magnetite, 
pyrite, zircon, rutile, a pyroxenic mineral, and a doubtful grain of apatite. The structure is 
a fairly uniform mosaic. 

Quartz is in numerous irregular grains, which extinguish normally. Some of these replace 
original feldspar. 

Biotite occurs in small irregular plates wrjipping round the quartz and feldspar, one or two 
of which are rather decomposed and may be original. The rest are of secondary origin. 

Feldspar was originally fairly plentiful, but much, if not all, is now silicified. When the 
original feldspar is replaced by a sing'e quartz grain, cleavage and even twinning may be 
preserved, and it is difficult to be certain as to replacement.r A few grains show albite twinning 
with extinction generally at a small angle to the twinning-plaue. 

Magnetite is not common, but there is a good deal of pyrite. 

There are many small grains of zircon with rounded outlines scattered through the 
section. 

Rutile probably occurs as sagenitic needles in a few of the biotites. 

liemarks. — It is probable that the original rock was a grauwacke similar to those of the 
Greenland Series. Possibly it rej)rt'sents a fragment from the horizon of the gneissic schists, 
wliicli was imprisoned in the granites at the time of their intrusion. 

5. From grauwacke inclusion in tourmaline-pegmatite, Anderson Creek, north side of 
Waitaha Sugarloaf. 

The hand-specimen is a grey indurated grauwacke -hke rock of fairly fine grain. 

Under the microscope the section is seen to consist almost wholly of quartz and biotite. 
.A. little magnetite is almost the only other mineral present. 

Quartz m rounded or irregular interlocking grains forms the greater part of the section. 
There are many silicified feldspar grains, in one or two of which traces of albite twinning may 
be observed. 



186 

Biotite, associated with a few small grains of magnetite, occurs in the same way as in 
section No. 4. No rutile needles, however, , were observed. 

Remarks. — The original rock was a grauwacke of the Greenland Series. 

Metamorphic Effects. 

As stated in an earlier part of this bulletin, the metamorphic effects of the granite in- 
trusions are of a remarkable character, especially in connection with the gneisses and dark 
schists of the Arahura Series. Since the thermal metamorphism caused by the granite in- 
trusions is compUcated by the factors of dynamic stress and the heat produced by reUef 
of internal strains, as well as by the internal heat of the earth acting on deeply buried strata, it 
is clear that the exact influence of the granite intrusion cannot be estimated. We have also 
to take into account the origmal nature of the metamorphosed rocks themselves. Somewhat 
peculiar is the fact that we see in the gneissic schists no metalliferous lodes — as. for example, 
those of tin — such as might reasonably be expected. 

In all cases the Arahura rocks near the granite and at distances half a mile or more from 
the surface contacts are thoroughly recrystalhzed, and thermal metamorphism can be traced to 
the eastern boundary of the lower dark schists. Probably, however, granite underlies the 
completely altered rocks at moderate depths, so that the metamorphism has proceeded 
from below upw'ards to at least as great an extent as from the plutonic bosses horizontally 
outwards. Apparent bedding-planes are often observable, but since these coincide in direction 
with the schistosity induced by movements due to differential pressure during the period 
of mountam-building, there is room for doubt. Bedding, however, is often indicated also 
by variations in the texture of the rock, and its mineral composition may also be considered 
a guide. 

The rocks beUeved to have been originally sedimentar}- may consist mainly of a flinty 
quartz, or of quartz and soda-lime feldspar (chiefly oUgoclase) with some biotite or muscovite 
or both. The chief decomposition-products are quartz, epidote, kaolinitic matter, pyrite, &c. 

Certain other rocks, largely developed from the upper valley of Doctor Creek to the Mikonui 
and Kakapotahi valleys, have as probable products of the thermal metamorphism a green, 
highly pleochroic hornblende (often urahtic), forming the most prominent mineral, together 
with pyroxene (rarely unaltered), oligoclase or other soda-lime feldspar, biotite, occasional 
musco\dte, quartz, titaniferous magnetite and ilmenite, rutile, garnet, apatite, and zircon. 
On the east side of Mount Bonar tourmaUne is rather abundant in large crystals. The 
probable subsequent decomjiosition or alteration products include urahtic hornblende, a 
less pleochroic amphibole in small prisms, leucoxenic titanite, epidote and cUnozoisite, 
calcite, biotite, muscovite and sericite, haematite, pyrite, &c. 

The apatite and zircon of the first list may possibly represent origmal constituents of 
igneous rocks which have suffered practically no change during the whole metamorphic 
period. The abundant iron, and more especially titaniferous minerals, as well as the amount 
of soda and potash present, seem also to point to primarv igneous rocks, but what their 
condition was when the final metamorphism began is impossible to determine. 

The prominent minerals produced mainly by thermal metamorphism in the dark schists 
are green hornblende, augite or other pyroxene (now very rare), soda-hme feldspar, biotite. 
muscovite, (|uartz, garnet, titaniferous magnetite and possibly ilmenite, rutile, and a mineral 
doubtfully referred to woUastonite. The hornblende, perhaps largely derived from pyroxene, 
is believed to be developed only where the plutonic rock underlies at no great depth. 
Secondarj' minerals due to subsequent alteration are leucoxene, amphibole of different 
character to the green hornblende, occasional serpentine, epidote, calcite, quartz, haematite, 
pyrite, kaoUnitic matter, &c. 

Though, owiag to the various complications, it is very difficult to differentiate at all satis- 
factorily between the minerals produced mainly by thermal metamorphism and those due 



137 

rather to regional raetamorphisni. the lists given above are at least suggestive. They may be 
compared wnth the follow uig lists given by Van Hise as produced by the Black Hills granite 
bathohth. In the adjoining gneiss are quartz, mica, feldspar, garnet, staui-olite, hornblende, 
and tourmaline. Further away the rock is a quartz -mica-schist, with staurolite and garnet 
in addition to (|uartz and mica.* 

The boundary-line between the dark schists (which are supposed to be mainly of igneous 
origin) and the ordinary quartz-mica-schists (considered to be derived from sedimentary rocks) 
is thought to mark fairly well the extreme eastern limit of the thermal metamorphism, due 
mainly to the granite intrusions. Nevertheless, the metamorphism of the quartz-mica-schists 
is largely thermal, and, though generally attributable to the internal heat of the earth, locally 
increased by conversion of the energy producing mountain-building into heat, may also be 
imagined as assisted to some extent by the magma which gave rise to the granite bosses. It 
may be mentioned here that, in addition to quartz and mica, garnet and magnetite are the 
most common minerals in the ((uartz-mica-schists. 

In the Greenland Series the metamoiphic effects of the granite are much less complicated. 
To distances of a quarter of a mile and occasionally a mile from the contact the rocks become 
highlv biotitic, thus acquiring a characteristic sheen, and the feldspar fragments are silicified. 
In tins wa\ the original structure is largely obliterated, and an incipient schi.stosity is 
developed. 

It is e\'ident, however, that these changes. are caused not by circulating solutions, but 
bv interchanges of the molecules within limited areas, under the intiuence of heat, aided no 
doubt bv small quantities of water. They are, in fact, strictly of the kind termed meta- 
somatic. It is thought that where metamorphism is apparent in these rocks at considerable 
di.stances from the contact with plutonic rock, granite underUes at no great distance. 

Evidence of hydrothermal action accompanying or following the granite intrusions is 
furnished by (juartz veins which penetrate the grauwackes of the Greenland Series. Some 
of these mav be older than the granite intrusions, but there are others near the contacts which 
may, with some confidence, be referred to the intnision period. These are characterized 
by a peculiarly glassy quartz, often with a little muscoN-ite, and a remarkable absence of 
metallic minerals. They therefore approximate to greisen veins. 

If the pyritic vein of the Rangitoto Mine hves down into the neighbouring granite (see 
<'ha[)ter XIV) it must be younger than the granite, and is probably associated mth the 
hydrothermal processes followins; the plutonic intrusions. It would then be the one known 
example in the Mikonui Subdivision of a possible payable vein formed in this way. 

The apparentlv limited amount of hydrothermal action is somewhat discouraging from 
an economic point of view, for the purely thermal metamorphism which is .so largely developed 
in the Greenland Series is not hkely to have caused the concentration of valuable minerals 
into workable deposits. 

• " A Treatise on .Metamorphism," Monoerraphs of TJ..S. Oeol. Survey, vol. xlvii. 1904, p. 717- 



13ft 



CHAPTER XIIL 



THE BASIC IGNEOUS ROCKS OF THE MIKONUI SUBDIVISION. 



Page Pase 

Mode of Occurrence . . . . . . 138 General Petrology . . . . . . 139 

General Distribution, Width, Strike, and Special Petrology .. .. .. 140 

Dip of Basic Dykes . . 138 Analyses . . . . . . . . 141 

Age and Correlation . . 138 

* 

Mode of Occurrence. 

The basic igneous rocks here described occur as dykes penetrating the granites, gneissic 
schists, and coal-measures. Unless the ultra-basic rocks of the Pounamu Formation be taken 
as their equivalents, the dyke rocks are not represented in the middle and upper parts of the 
Arahura Series, nor were basic dykes observed in any part of the Greenland Series. 

Numerous loose boulders indicate the existence of a surface effusion of oli^ane-basalt in 
the watershed of Humbug Creek, similar to that described in the Hokitika Bulletin as occurring 
on Koiterangi Hill just outside the subdivision.* No outcrop, however, of this particular rock 
could be found, probably owing to the dense covermg of forest vegetation. 

General Distribution, Width, Strike, and Dip of Basic Dykes. 

Basic dykes occur on the east side of Mount Misery, where in the gneissic schists they are 
remarkably numerous, as many as sixteen having been observed in a distance of a few 
hundred yards ; at the north end of Doctor Hill, in granite ; at Humbug Creek, in the coal- 
measures ; in the lower Tuke River, on the west side of the Kakapotahi Valley, at Mount 
Bonar, in gneissic schist ; and at Mount Rangitoto, in granite. 

Grenerally the dykes are from 2 ft. to 6 ft. in width, but their dimensions in this respect 
vary from a few inches to 30 ft. They invariably dip almost vertically, and, when enclosed 
in gneiss or gneissic schist, usually strike in the direction of schistosity. In the granite they 
have no general direction other than that of the master joints. 

Age and Correlation. 

Since basic dykes cut rocks of the coal-measures, and at Koiterangi Hill the olivine-basalt 
apparently rests on a denuded surface of the conglomerates, it may be inferr d that all the 
basic dykes are of post-Koiterangi age. It is, however, qmte possible that those dykes which 
cut the granitic and gneissic rocks are older. If the opinion adopted in the last chapter con- 
cerning the age of the granite intrusions be correct, the rocks in question may have immediately 
followed the irruption of the acid plutonics. This view is supported by the close association 
between the basic dykes and the granites and gneisses which appear along the western margin 
of the alpine chain, but no direct e\adence in its favour has been obtaiaed. 

The basic dykes and volcanics of Westland are iindoubtedly more or less contemporaneous 
with some of the volcanic rocks of Central Canterbury, Banks Peninsula, the neighbour- 
hood of Dimedin, and Central Otago, as well as with the Tertiary volcanics of Coromandel 
Peninsula and the North Island generally. 



• Bulk No. 1 (New Series), N.Z.G.S., 1906, p. 84. 



139 

The frequent occurrence of Tertiary basic volcanic rocks and dykes among the foothills on 
the eastern side of the Alps* certainly seems to indicate that these at least will prove to be 
closely connected with those on the western side. 

A correlation between the basic dykes and the ultra-basic rocks of the Pounamu Forma- 
tion, as suggested in the Hokitika Bulletin.f is at least possible, but difficult to prove. Tt 
is probable, however, that acid plutonics, ultra-basic rocks, and basic dykes quickly 
succeeded one another, and were expressions of the orogenic movements which have built 
up the Alps. 

General Petrology. 

Petrologically the basic dykes present some variety. Occasionally they are so decom- 
posed as to be identifiable with difficulty, but the fresher dyke rocks may be described as 
homblendc-camptonites, augite-camptonites, altered (uralitic) augite-poi-phyrites, altered 
diabases, olivine-diorite, basic quartz-diorite, and extremely basic basalt (with altered olivine) 
of different type from that forming the middle knob of Koiterangi Hill. 

' With the exception of the basaltic rocks, the various types are similar in composition, and 
in a classification that was mainly chemical would be embraced by two or at most three names. 
Many of the rocks present the structures typical of dyke rocks, but not a few, particulary of the 
larger dykes, show a tendency to structures more characteristic of plutonic rocks. Only in two 
sections was undoubted residual volcanic glass seen, and then only in small quantity, but in one 
or two others chloritic matter was considered to represent original glass. 

The description of the basic dykes occurring iji the Hokitika Subdivision given in the 
Hokitika Bulletin applies in a general way to those of the Mikonui Subdivision, where nearly 
the same range of dyke rocks occurs, so that only the briefest indications of general petro- 
logical character need here be given. It may be remarked, however, that true porphyrites 
are of much less common occurrence in the Mikonui Subdivision than further north. 

The hornblende-camptonites art; perhaps the commonest form of dyke within the sub- 
division. Typically they consist of abundant hornblende with a rather acid plagioclase, and 
titaniferous magnetite, with occasional biotite and apatite. 

The augite-camptonites are analogous to the hornblende-camptonites, but in the specimen 
examined titaniferous magnetite is more plentiful, and ilmeuite is certainly present. 

The altered augite-porphyrites and diabases are fairly common as dyke rocks. They 
grade into one another, as well as into camptonites, and more especially diorites. They are 
seldom or never typicitlly porphyritic in structure, or diabasic, as the case may be. The 
original minerals present are augite. always more or less uralitized, rather acid feldspars, 
occasional biotite in sjuall quantity, titaniferoiis magnetite, and probably ilmenitc. 

Olivine-diorite was observed in only one instance. The section made of this interesting 
rock is described under the next heading, together with one of a thoroughly basic diorite, con- 
taining some primary quartz. 

The extremely basic rock (No. 3) from Humbug Creek must be called a basalt from its 
general characters. The lowness of the silica-percentage is remarkable. It is to a slight 
extent due to subsequent alteration, with introduction of carbon-dioxide and water, and 
possible remo»ral of a little silica. The rock may bo compared to certain furnace slags, low 
in silica but high m alumina, and the extraordinarily high percentage of the latter oxide sug- 
gests that possibly it here plays an acid part, taking the place of silica. 

All the dyke rocks exhibit more or less alteration, some indeed becoming almost unre- 
cognisable. Calcite is perhaps the most common decomposition-product, whilst others are 
epidote, quartz, chlorite, leucoxene, haematite, ppite, talc, and serpentine. 

A few of the dykes enclosed in gneissic schist have been affected by dynamic stresses, 
and have acquired a somewhat schistose structure. 

* For example, in the Trelissic basin, at Springfield, &c. See also Von Haast, " Geology of Canterbury 
and Westland," pp. 300, 313. ' In this^connection read, moreover, pp. 281-290. 
t Bull. Na 1 (Now Series), N.Z.G.S., p. 68. 



140 

(Special Petrology. 

1. From loose boulder, Shadow Stream, off Doctor Creek. 

The hand-specimen is a dark, heavy, coarsely crvstalUne rock, apparently consisting 
almost wholly of a black amphibole with lustrous cleavage surfaces and a few scales of golden - 
brown, highly lustrous mica. It effervesces slightly with acid. 

Under the microscope the following minerals are seen in the section : Hornblende, ohvine, 
plagioclase, biotite, or other pleochroic mica, magnetite, pyrihotite (?), calcite, chlorite, and 
glassy material. The general structuie is hypidiomorphic. (Plate XXVI, Xo. 2.) 

Hornblende forms far the greater part of the rock. The pleochroism is from moderate 
Ught-browai to nearly colourless. 

Olivine is in rounded or irregular patches of various sizes, all except the largest being en- 
closed in hornblende. It is greatly cracked, vvith much dark material along the breaks, but is 
nearlv always fresh. One or two grains show alteration along the edges to a carbonate. 

Most of the plagioclastic feldspar is fairly well twinned, and is probably near acid labra- 
dorite. but is difficult to determine, largely because of a peculiar, somewhat undulose ex- 
tinction which appears athwart the albite-t^\^nned lamina-, giving a patchwork appearance, 
and is no doubt due to an imperfect pericline twinning. One grain at least seems to be of 
a more acid type. The feldspar shows slight alteration to carbonate, &c. 

The biotitic mica is in large plates, with fine pleochroism. a beautiful reddish-brown to 
nearlv colourless. Twinning is frequently developed. More exact in\'estigation might identify 
the mineral as anomite (Roseubusch), or some other variety of pleochroic mica. 

Magnetite is not very abundant in the section. A number of small dark grains and the 
dark dust are presumably to be referred to this mineral. 

A metalhc sulphide which by its coloui- and lustre seems to be pyrrhotite occurs in 
abundance in the section. It is in fiesh rounded grains, or occasionally in laths. From its 
mode of occurrence it certainly appears to be original. 

Calcite occurs as a decomposition -product, and there are also two or tluee well-twinned 
plates embedded amongst the other minerals, which seem to be of primary origin. This 
appearance, of course, is probably deceptive. 

Green chlorite appears in small patches as a decomposition-product of biotite and horn- 
blende. 

The glassy material occurs as small rounded brownish-green grains or patches enclosed 
in olivine, feldspar, or hornblende. These often include a good deal of dark material, and 
are more abundant in certain parts of the section than others. 

Ketnarks. — The rock may be called an oU\'ine-diorite.* Though not foimd m situ, it may 
be referred to a large dj^ke in the Mount Misery granite. 

2. From Happy Creek, west side of Kakapotahi River. 

The hand-specimen is from a 6 ft. dyke in gneissic schist. It is a coarsely crystalline 
rock, composed mainly of a black amphibole, with scattered white spots of feldspar. 

Under the microscope the following minerals are seen to be present : Hornblende, plagio- 
clase, quartz, magnetite, haematite, pyrrhotite (?), titanite, epidote. The structure is hypidio- 
morphic. 

Hornblende is very abundant, showing characteristic cleavage and pleochroism (bluish- 
green to light-green to pale greenish-yellow). Twinning bands occasionally appear in the 
longitudinal sections. There is a strong tendency to assume idiomorphic outlines, which is 
never qtiite successful. 

The plagioclase is mainly fairly fresh labradorite, with both albite and pericline 
twinning. It often shows very marked zonary structure, the more acid feldspar outside being 
perhaps oligoclase. 

* Exception may be taken to this naming of a dyke rock as diorite, particularly since apparent glaasy 
matter is present. 



PLATE XXVI. 






^^ICHO-PHOTOGK.APHS BY Dr. P. MaKSHALL. 

1. Hornblende-ooniptonite. froin dyke in Supply Creek granite. The principal minerals present are 

hornblende, basic oliy<)( lase. and magnetite. 

2. Olivine-diorite, from loose boulder in Shadow Stream. 

3. Basaltic rock, Humbug Creek. The illustration shows phenocrysts of augite and plagioclase On the 

left are two patches of chlorite and talc. The dark base is principally magnetite. 

No. 1 is magnified about 30 diameters; the others 25 diameters. 



Geol. Bull. No. 6.] 



[To face fage HO. 



141 



Quartz, considering the nature of the rock, is rather plentiful in uests and isolated grains 
which are of primarv origin. It also occius with epidote as a tine mosaic on the borders 
of the feldspars. 

There is not much magnetite ui the section. Some is further oxidized to haematite. 
The supposed pyrrhotite is in rounded grains, which on the borders decompose to haematite. 
(Compare with section No. I.) 

A few small grains and rhomboids of titanite appear in the section. 

Hemarks.—Thv rock may be called a (juartz-diorite. but the predominance of hornblende 
gives it a thoroughly basic character. From the analysis given below it will be seen that 
the silica-percentage is only 47 44. 

3. From dyke-like mass penetrating coal-measures, Humbug Creek. 

The hand-specimen is a dark, heavy rock which noticeably affects a magnetic needle. 

Under the microscope it is seen to consist of augite, plagioclase, magnetite, talc, 
chlorite, and small patches of glassy matter. (Plate XXVI. No. 3.) 

The augite is in immerous well-defined phenocrysta. It has a brownish-violet tint, with 
slight pleochroism. and contains inclusions of magnetite and patches of the matrix. 

Feldspar is in numerous laths of various dimensions, with albite twinning moderately 
developed, whilst one square cross-section exhibits a well-defined Carlsbad twin. By the 
extinction-angles it is largelv labradorite, but an increase of acidity from the centre outwards 
is often noticeable. With magnetite it forms the matrix of the augite phenocrysts. 

Magnetite is plentiful in grains, which tend to develop a square cross-section. 

Decomposed phenocrysts of a mineral which by the outlines may once have been olivine 
now appear as vellowinh aggregates, consisting principally of talc with some chlorite and pos- 
sibly serpentine. 

The glassv matter forms small yellowish patches enclosmg more or less dark material, 
filling the spaces between the feldspar laths, Ac. 

Remarks. — The rock might be called a basalt, but the analysis (No. 1) which follows 
shows that it is of extremely basic character. 

Analysers. 
The following five analyses of dyke rocks will prove of interest, and repay study : — 



Silica (SiO J 

Alumina (AljOj) 

Ferric oxide (FcjO 3) 

Ferrous oxide (FeO) 

Manganous oxide (MnO) .. 

Jiime (CaO) 

Magnesia (MgO) .. 

Potash (K.,()) .. 

Soda (No^O) 

Titanium • oxide (TiO 2) 

Sulphur-tnoxide (SO3) 

Chromic oxide (CtjOj) 

Sulphur and iron in form of pvrite (FeS,)'* 

Carbonic anhydride (CO,) 

Loss on ignition (excluding CO,) .. 



1. 


2. 


3. 


4. 


5. 


.. 32-36 


50-82 


4909 


47-44 


41-00 


.. 2615 


16-58 


13-72 


11-81 


12-61 


5 04 


0-44 


0-95 


1-58 


0-63 


. . 10-30 


8-27 


7-27 


9-44 


8-08 


. 0-25 


0-25 


0-32 


0-39 


0-41 


10-74 


7-80 


8-35 


12-32 


1112 


.. 3-76 


8-31 


11-97 


12-30 


15-25 


.. 1-68 


1-89 


1-27 


1-09 


1-46 


. . 1-23 


2-34 


2-66 


1-12 


1-85 


.. 1-55 


1-12 


105 
0-10 


1-25 

• • 


1-12 


. . 05 


008 


009 


0-20 
0-23 


010 


.. 1-12 


0-35 


0-95 


0-05 


2- 13 


. . 5-66 


1-89 


1-96 


0-70 


4-19 



99-89 100-14 



99-75 



99-92 



99-95 



♦ The mineral is possibly pyrrhotite. 



142 

1. Dark, heavy rock (basic basalt) penetrating coal-measures at Humbug Creek. Petro- 
logically described as No. 3. 

2. Dyke of hornblende-camptonite in granite, Supply Creek, north end of Doctor Hill. 

3. From 30 ft. dyke of hornblende-camptonite in granite, Galena Gulch, Mount Rangitoto. 

4. Dyke of basic quartz-diorite in gneissic rock, Happy Creek, Kakapotahi River. Petro- 
logically described as No. 2. 

5. Diabasic dyke in gneissic schist, Tourmaline Creek, Waitaha River. 



143 



CHAPTER XIV. 



ECONOMIC GEOLOGY AND WATER-POWER. 



Metalliferous Veins of the Arahura Series 


Page 

143 


Axiriferous Alluvial Deposits . . 


Page 
151 


(1.) Quartz veins . . 


143 


(1.) River and Creek Gravels 


151 


(2.) Pyritic veins . . 


144 


(2.) Fluvio-glacial Gravels . . 


153 


Metalliferous Veins of the Greenland 




(3.) Beach-sands . . 


153 


Series 


144 


(4.) Special Area — Ross and Neighbour- 




Asbestos and Talc 


147 


hood 


153 


Building and Ornamental Stones 


149 


(5.) Origin of Auriferous Alluvial De- 




Limestones for Agricultural Purposes. &c. 


149 


posits 


155 


Road-metal 


150 


Prospecting 


156 


Clays 


150 


Water-power 


158 


C!oal 


151 


Summary . . 


161 



Mktalliperous Veins of the Arahura Series. 
(1.) Qxiartz Veins. — Quartz veins other than thin threads or the laminae formed during the 
period of metamorphisin are iiot numerous in any part of the Arahura Series as it occurs within 
the Mikonui SuhdiA-ision . Where they do occur, they generally run parallel to the stratifica- 
tion, and in nine cases out of ten appear to be entirely valueless ; but the presence of gold 
in the Arahura rocks is shown by the occurrence of fine colours in all the main rivers, and 
more particularly in the Whitcombe and in the Upper Hokitika, rivers which drain a con- 
siderable extent of the main di\'ide. Although it is certain that the rocks near the alpine crest 
are gold-bearing to a greater extent than the more schistose rocks to the west, it cannot be 
said that the auriferous belt of the Wilberforce district enters the Mikonui Subdivision at 
any point. Considering the enormous denudation which is taking place, the amount of al- 
luvial gold is small. Notwithstanding the extremely rugged nature of the country, portions 
have been thoroughly prospected for auriferous reefs, and consequently there can now be 
little expectation of finding payable lodes. 

There are numerous small veins and threads of quartz in the slates and grauwackes which 
appear near the main "divide. These are^probably slightly auriferous ; but only on Mathias 
Pass and near the Toaroha Saddle were lodes of any size seen.f ,No sample was taken of 
the Mathias Pass lode, which is well known and was.' doubtless tested many years ago. 
Though loose quartz near the Toaroha Saddle seemed to show rare fine colours of gold, two 
samples taken for assay from a small reef proved valueless. 

On the horizon of the Pounamu Formation there are a number of quartz lodes, one or two 
of considerable size. Gold, silver, and platinum, as in the''Hokitika 'Subdivision,'' occur in 
some of these veins, but only in minute quantities. 

The most promising veins in the Arahura rocks of the Mikouui Subdivision are two which 
outcrop on the Whitcombe Pass track, about a mile above the Holdtika-Whitcombe junction. 
The veins are close together, rnd^ are'' each about 1 ft. thick. They strike across the bedding 
of the enclosing" mica-schist — a-good.^ign — and\dip rather 'flatly. The Vein-quartz 'contains 
a good deal of pyrite. On being assayed, a sample from one of these lodes gave the following 

results :— Per Ton. Value per Ton. 

Oz. dwt. gr. £ 8. d. 

Gold ... .. .. .. .. 2 12 10 

Silver .. .. .. .. .. 1 16 2 

Copper . . . . . . . . 0-57 per cent. 



Total value per ton . . . . . . £0 10 2 



144 

A sample from a fairly promising-looking quartz lode outcropping in Grinuuond f 'reek, 
a branch of the Dickson River, on being assayed, proved devoid of value. 

(2.) Pyrilic Veins. — Associated more or less with the Pouuamu Formation, but not actually 
in it, are small veins consisting chiefly of pyrite. Tliese contain gold, silver, platinum, 
copper, and m one instance lead. Nowhere, however, could any deposit of a payable nature 
be discovered. 

A little to the westward of the talc outcrop of the Pounamu Formation in the Whakarira 
Gorge (Kokatahi River), in the wide band of talc-schist which there occurs, there is a vein 
of cupriferous pyrite, which is from 1 in. to 6 in. in thickness as exposed. Close at hand are 
several very small pockets of similar material, at most only a few feet long. The vein may 
possibly persist, but its thmning-out to an inch or two in a small drive which has been made 
at this spot is not a promising sign. Assays of various .samples resulted as follows ; — 

1. 2. 3. 

Gold . . . . Nil Nil 10 gr. per ton. 

Silver 



Platinum 

Copper 

Lead 



Nil. 

)» » »> 

'■S per cent. 0-5 per cent. 3-76 per cent. 

Nil -l-Qi .. Nil. 



£ 


3. 


d. 





4 











1 



A pyritic vein of small size which was discovered in Serpentine Creek enclosed in talc-schist, 

when assayed, yielded the following interesting results : — 

Per Ton. Value per Ton. 

Oz. dwt. gr. £ s. d. 

Gold . . . . . . . . . . 1 10 5 8 

Silver .. .. .. .. ' ..012 001 

Platinum .. .. .. ..004 

Copper . . . . . . . . 0-79 per cent. 

An assav made of similar material from a large loose boulder in the Toaroha River gave 

the equally interesting results : — Per Ton. Value per Ton. 

Oz. dwt. gr. 

Gold .. .. 10 

SHver .. .. .. .. . . 20 

Platinum .. .. .. . . 15 

Copper . . . . 2-23 per cent. 

The very close agreement in proportion of gold to silver and of platinum to copper m 
each of these analyses is most remarkable. 

Metalliferous Veins of the Greenland Series. 

It has been repeatedly stated by McKay that the grauwackes and slates of the Green- 
land Series are identical in age with the auriferous rocks at Reefton. However uncertain 
the correlation may be, there can be no doubt about a resemblance in the auriferous characters. 
Small quartz veins are found everywhere in these rocks, and in the neighbourhood of Ross 
often contain coarse specks of gold. Hitherto, however, notwithstanding many trials, no 
payable gold-mine has been brought into operation, though at the present time one promising 
venture is being developed by Osmers and party near Ross. 

1 Several small quartz veins (bedded) exist in the grauwaoke of the western part of Koite- 
rangi Hill. One of these, which was tested many years ago, gave, it is stated, an assay of 
several pennyweights of gold per ton. 

In the lower part of Doctor Creek several bedded quartz veins of various sizes were seen. 
The only metallic mineral present is a little pyrite. A sample from the largest, on being tested 
by assay, gave negative results. In Humbug Creek, a tributary of Doctor Creek, there are 
several large bedded veins which apparently owe their existence to the hydrothermal after- 
effects of the neighbouring granite intrusions. All are so exceedingly hungry-looking that 
it was deemed useless to take assay samples. The unpromising nature of the Doctor Creek 

/ 



PLATE XXVII. 




Vii;w 



\Vi:sT OK South kkom Mount Met.\, siiowinc; Pakt of Lancie 1{an(.!e in distance, 
WITH Mount Evans and Pahk Dome to right. 




lEW i.ooKiNt: Wkst fhom .Mount .Mi;ta of Si.opks of .Mount Howen. Sehpentine-uunite out- 
citops on Ridge to left of Creek Valley (Brow Creek) 



Gtol. Bull. Xo. 0.] 



[To face mujt llflf. 



14/5 

watershed is further indicated by the romplete absence of all but the smallest traces of alluvial 
gold from the stream-beds. 

In the valleys of the Totara River and its numerous tributaries there are many quartz 
lodes of various sizes. Some of these were tested by crushing and panning-off, but gave nega- 
tive results. This locality is verv' accessible, and has been thoroughly prospected, so that, 
notwithstanding the occurrence of a little gold in many of the creeks which appears to be 
of direct lode origin — that is, not derived from any of the older gravels — there can be little hope 
of an>'thing of a payable nature. 

At the head of Farmer Creek the late Antonio Zala carried on prospecting operations 
for several years. He located several lodes which probably gave dish prospects, for a small 
batterv' was erected to crush the ore, but the results were not satisfactory. A sample taken 
from one of the quartz outcrops gave— Gold, 060 gr. per ton ; silver, nil. 

A sample from a lode in Weir Creek gave on assay neither gold nor silver. This particular 
area is therefore not a promising one. 

In the valleys of Donnelly Creek and its tributaries arc many small veins from which 
small pieces of visibly auriferous quartz have often been obtained. Many years ago, as 
mentioned on page 25, some of these, in the valley of Bayley Creek, were worked for short 
periods. 

Somewhat higher up Bayley Creek a lode about 6 in. in thickness with a strike of about 
336° was discovered by Osmers and party about two years ago. It has been traced for 
some distance on the surface, and wherever tested showed colours of gold. Drives have 
been constructed along the course of the reef, and a considerable section opened up. Samples 
broken in the presence of the writer showed visible gold, and gave excellent dish prospects. 
Towards the end of 1907 a small battery was erected by the owners, and since then several 
crushings have been made.* 

The history of the quartz-mines at the head of Cedar Creek, where a considerable amount 
of prospecting and other w(uk was done twenty years ago and more, was given in Chapter II. 
The quartz veins are encased in argillite (slate), and on the whole follow its bedding, though 
rather irreguUrlv. The mam lode is from 2 ft. to 4 ft. thick where seen, strikes west-north - 
west and cast-south-east, and dips north-north-east. Some pyrite and oxide of iron are 
\nsible in the vein- quartz, whilst loose pieces picked up in the neighbourhood show occasional 
colours of gold. Twf) samples which showed no visible gold were taken for assay, and 

vielded : — Gold per Ton. Silver per Ton. Value per Ton. 

Dwt. gr. Dwt. gr. £ 3. d. 

No. 1 ..16 22 051 

No. 2 ..16 16 051 

It is stated by Mr. H. A. Gordon, formerly Inspecting Engineer of the Mines Department, 
that in a wijize simk on this lode excellent prospects were obtained to a depth of 20 ft., but that 
the lode then began to peter out.f An adit level driven on the lode for a distance of 229 ft. 
showed, it is said by the same gentieman, payable stone for 200ft.t It was impossible 
for the old workings to be examined in detail at the time of the liter's visit, owing to their 
partial collapse. The known occurrence of payable stone would seem to justify further pro- 
specting ; but, on the other hand, the past history of the mines is anything but encouraging. 
It is a matter of common report, however, that the old operations were haphazard and incom- 
petent, and, it may be, were so ill-directed as to be of little value in proving the lodes one 
wav or the other. 

At the small bluff on the north side of the Mikonui, near Gribben's homestead, is a small 
lode, 4 in. to 6 in. thick, which strikes about 220^ It carries a little pyrite, and the 
fact that it crosses the bedding of the enclosing grauwacke raised an expectation that it might 
be gold-bearing, but a careful panning of the roasted ore failed to yield a colour. 

• See also p. 25. t Mines Report, 1888. C-S, p. 39. J Mines Report, 1889. C'.-2, p. 51. 

lO'Mikonai. 



146 



A sample from a lode somewhat similar to the last, outcropping in the lower part of Slate 
■ Creek, half a mile away, gave on assay negative results also. 

Near the head of Shearer Creek, a rather promising-looking bedded quartz reef 2 ft. 
to 4 ft. thick was seen. A sample on analysis gave— Gold, 8 gr. per ton ; silver, 1 dui;. 13 gr. 
per ton : value per ton. Is. 8d. 

A sample from one of the lodes in Bullock Creek, on assay, failed to yield either gold or silver. 

In the valley of the Kakapotahi the only mineral lodes located were on the western slope 
of Mount Rangitoto, in Mine Creek. A quartz vein in grauwacke, near the lower granite 
contact, shows a considerable proportion of copper-carbonate and chalcopyrite, but is too 
small to be of any value. 

Higher up Mine Creek is the outcrop of the vein exploited by the old Rangitoto Silver- 
mining Company. The vein is seen outcropping in the creek, and is encased in grauwacke, but 
is said to have been followed into the neighbouring granite. The lode as visible is from 
2 in. to 6 in. thick, and dips very flatly to the north-north-west. According to Cox the dip 
in the old workings is 30° and more, whilst the thickness reaches 10 in. The lode matter is 
a mixture of quartz and pyrite, with a minor amount of galena. A general sample from the 
outcrop gave the following results 

Gold . . 

Silver 

Copper 

Zinc'.. 

Lead 

Total value per ton . . . . . . £5 12 6 

* 

A general sample taken from the broken ore lying near the mouth of the adjoining drive 
yielded : — ■ 

Gold . . 
Silver 
Copper 
Zinc j . . 
Lead 

Total value per ton 

About the year 1876 a considerable number of analyses of Rangitoto ore were made 
by the late Mr. WilUam Skey, formerly Colonial Analyst. His results^ may be summarised 
as follows : — 



Per Ton. 


Value per Ton. 


Oz. dwt. gr. 


£ s. d. 


..155 


5 10 


.. 4 16 9 


11 8 


Nil. 




Nil. 




1-87 per cent.* 





Per Ton. 
Oz. dwt. gr. 
..1 3 22 


Value per Ton 
£ 8. d. 
4 15 8 


..2 5 23 


5 6 


Nil. 




Nil. 




0-2 per cent.f 





.. 


£5 1 2 




* Equivalent to 209 per cent, of galena. f Equivalent to 0-2.'? per cent, of galena. J " Eleventh 

Annual Report on the Colonial Museum and Laboratory," 1876. pp. 22-24; Twelfth ditto, 1878, pp. 32-3S. 



147 

Nos. C) and 7 are said to conic from a point 35 ft. along the face of the lode, No. 8 
from 20 ft. along the face, and No. 9 from a vein 40 ft. along the face. Mr. Skey 
remarks upon these four samples : " These results are upon specimens collected for the purpose 
of getting reliable data as to the true character of the lode to that time prospected, and it 
is seen that they in no way tend to support the belief that the Rangitoto ore is Hkely to be 
a paying ore as regards the extraction of silver."* 

Von Haast states that an analysis of Rangitoto ore made for hiju by Professor Bickerton 
of Canterbury College, showed 94 oz. of silver per ton, with an appreciable amount of gold, 
and 11-4 per cent, of lead.f Skey states that two samples of the ore sent to Germany yielded 
silver at the rate of 17 oz. 19 dwi;. per ton, and 16 oz. 6 dvrt. per ton respectively, besides 
some gold, and apparently a considerable proportion of lead.f These were probably 
picked samples. He also states that Professor Bickerton and Mr. Isaac Lewis made assays 
which showed 69 oz. and 46 oz. of silver per ton (? of galena), whilst at an earlier date Pro- 
fessor Kirkland, of I\Ielbourne, obtained from supposed Rangitoto ore the extraordinary 
results of 392 oz. and 735 oz. of silver per ton. He mentions also a report that a sample of 
the ore yielded gold at the rate of 500 oz. per ton. 

Skey further remarks that since all these assays were made upon ores of a similar kii;d, 
the accuracy of the methods employed may be questioned.§ From the facts as given, a more 
probable inference is that some of the samples were not representative of the Rangitoto ore. 

^\^^en the wTiter visited the locality the main drive of the Rangitoto Mine had collapsed, 
so that he was unable to make any examination of the old workings. Cox states that a face 
of about 35 ft. was exposed along the strike of the lode at the time of his examination. The 
character of the lode was uniform throughout, consisting of p}Tite, with about 20 per cent, 
of galena. A sample taken by him from the mine yielded 1 oz. 17 dwt. of silver per ton, but 
the gold was apparently not determiiied. After discussing the probabilities from a theoretical 
point of view. Cox came to the conclusion that the conditions for payable ore were on the 
whole favourable, but remarks that " the present outcrop is not of sufficient value to work on 
its own account."! I 

Owing probably to the Rangitoto Mine having been promoted as a silver and lead mine, 
very little attention seems to have been paid to the gold-content of the ore. This is un- 
doubtedly considerable in some samples, and, though from the assays quoted it appears to be 
very irregularly distributed through the lode material, there is room for supposing that 
this may not be the case. As concluded by Cox and Skey, the lode is valueless as a silver- 
lead proposition, but deserves further trial as a possible gold-producer. 

The decomposed granites of Mount Rangitoto have been reported gold-bearing, but the 
writer did not see any sigiis of mineralisation. If the Rangitoto lode passes from the enclosing 
grauwacke into the granite, as may be the case, it is not improbable that the adjoining 
granite may be somewhat auriferous. A sample of decomposed granite taken from another 
part of the mountain, on being carefully analysed for traces of gold, gave a negative result. 

Asbestos and Talc. 
As indicated on a fonner page, more or less talc and asbestos are associated with the 
Pounamu Fonnation wherever it occurs. The asbestos is always in small pockets and veins 
enclosed in or penetrating serpentine. It is often of fine quality, but could nowhere be found 
in commercially workable deposits. Talc occurs in much the same manner, as crystallized pure 
white or delicate apple-green masses of great purity. Such talc, if found in quantity, would be 
of considerable value for toilet preparations, &c. ; but the limited extent of the veins, and the 



* •• Twelfth .Annual Report on the Colonial Mu.seum and Laboratory," 1878, p. 33. 
t " Geology of Canterbury and Westland," 1879, p. 259. 

X " Twelfth Annual Report on the Colonial Museum and Laboratory. " 1878, p. 33. 
§ " Eleventh Annual Report on the Colonial Museum and Laboratory," 1876, p. 23. 
II " Report on the Westland District," G.S. Rep. during 1874-6, vol. x, 1877, p. 89, 

10'— Mikouui. 



148 

inaccessible localities in which the iniueral is fouiid, forbid any idea of its being economically 
utilised. 

Massive talc is found in large quantity, but is often very ijupure, and the lack of a New 
Zealand market, as well as the remoteness of nearly all the occurrences from roaded country, 
renders the mineral quite valueless at the present time. 

Occurrences of Asbestos. — A small asbestos vein of remarkably fine quality occurs in the 
talc-serpentine sill near Mount Jumbletop. The asbestos is in puxe white fibres several inches 
long, with a beautiful silky lustre. The analysis given below shows that it is true asbestos, and 
not chrysotile, the fibrous serpentine which forms much of the asbestos of commerce. 

In Tom and Dick creeks, which descend from the slopes of Mount Inframeta into the 
Whitcombe River, asbestos of ver}' good qviality was found in small pockets in talcose ser- 
pentine. That from Dick Creek is in remarkably fine fibres, which mat together like a 
felt. Associated with the serpentine on the slopes of Mount Bowen one or two small veins and 
pockets of asbestos were found. Some of the asbestos is of good quality, but much seems 
soft and talcose. 

Four analyses of asbestos are appended — -No. 1 is from Jumbletop, whilst No. 2 comes 
from Tom Creek, No. 3 from Dick Creek, and No. 4 from Mount Bowen : — 





No. 1. 


No. 2. 


No. 3. 


No. 4. 


Silica (SiOj) 


. 60-05 


55-70 


56-90 


56-65 


Alumina (AI2O3) . . 


2-44 


1-58 


1-31 


0-69 


Ferric oxide (FcjOg) 


2-72 


Nil 


0-16 


0-20 


Ferrous oxide (FuO) 


0-20 


6-27 


2-13 


3-21 


Manganous oxide (MnO) . . 


0-25 


0-55 


0-40 


0-35 


Lime (Ci^O) 


9-30 


12-80 


12-95 


11-00 


Magnesia (MgO) . . 


24-20 


20-32 


2413 


25-01 


Alkalis (K2O, NajO) 


* 


0-25 


0-30 


0-30 


Chromic oxide (CrjOg) 


* 


0-08 


Nil 


Nil. 


Carbonic anhydride (COj) 


* 


Nil 


Nil 


Nil. 


Water . . 


0-80 


1-48 


1-55 


2-25 



99-96 



99-03 



99-83 



99-66 



Occurrences of Talc. — .At Whakarira Gorge (Kokatahi River) the talcose band is about 
30ft. thick, but is rather impure. On Jumbletop there is a band of talc about 20 ft. thick 
associated with the serpentine, but it is apparently of no great length. Though dark in 
colour, it appears to be tolerably pure. East of this is a band of ferruginous impure talc, 
which occurs in the form of a sill over a mile long. The thickness of the band where examined 
was between 20 ft. and 30 ft. A similar band forms the western belt of the Pounamu 
Formation on Mount Bowen. It appears to be both ferruginous and siliceous. 

The numerous bands of talcose schist which occur in the horizon of the middle schists 
were described' in Chapter VI. It cannot be said that any are likely ever to prove of value. 

Crystallized talc of great purity and beauty was found in Serpentine Creek and on the 
slopes of Mount Bowen. Other occurrences contain much dolomite or allied carbonate. Of 
the following analyses. No. 1 is that of a white impure talc from Serpentine Creek, containing 
a large percentage of dolomite ; No. 2 is the analysis of a beautiful crystallized pale apple-green 
talc from Mount Bowen ; No. 3 represents a soft white compact talc, also from Mount Bowen ; 
whilst No. 4 is an analysis of an impure green talc -schist from a band east of the Pounamu 
Formation outcrop in Whakarira Gorge. The occurrence of 0'20 per cent, of chromic oxide 
in this last case indicates th"t the fine green colour exhibited by many of the talc-schists is 



Not determined. 



149 

partly due tf) chroniiuiii. and apparently proves a comiection with the Pounamu Forma- 
tion : — 

, No. 1. No. 2. No. .3. No. 4. 

Silica (SiOj) 37. 30 61-78 61-30 42-35 



Alumina (Al^Oj) . . o-50 0-40 0-48 

Ferric oxide (FejOs) ..Nil Nil Nil 



9-86 
1-68 
Ferrous oxide (FeO) 1-58 1-40 1-56 6-62 

0-28 



Manganous oxide (MnO) . 0-21 005 005 

Lime (CaO) ~.. 1203 Nil Nil 13-90 

Magnesia (MgO) 26-98 31-80 31-40 13-95 

Alkalis (NajO and K 2 O) 0-10 0-10 0-50 1-05 

Titanium-oxide (TiO,) . . Nil Nil Nil Nil. 

Chromic oxide (CrjjOj) Nil Nil Nil 0-20 

Carbonic anhydride (CO 2) 16-20* Nil Nil 7-38 

Water and loss on ignition 500 4-50 4-95 3-12 

99-90 10003 100-24 100-39 

BmLDING AND ORNAMENTAL StONES. 

These include grauwacke, serpentine, granite, and limestone. Many of the grauwackes 
of the Greenland Series might be used as building-stones if they occurred near localities where 
there was any demand for such mateiial. While hard and tough, they are generally fairly 
well jointed, and could be easily quarried — for example, in Donnelly Creek, near Ross. 

The serpentines of Mounts Bowen and Inframeta and the talc-serpentine of Jumblotop 
are usually handsome stones, suitable for ornamental indoor use, such as for small columns, 
mantelpieces, &c. They are not, however, equal in beauty to those of the Griffin Range, and 
the general inaccessibility (jf the outcrops seems to render them of no economic value. 

The granites of the Mikonui Subdivision, like those of the Hokitika area, are of varied 
quality. At Doughboy Hill there is an unlijnited supply of solid material in easily accessible 
positions, but the stone where exposed i,s nf)t well jointed, nor is it particularly handsome. 
In the lower part of Falls Creek a fine grey rock, with pale-pink feldspars, occurs in abund- 
ance. The stone is suitably jointed for quarrying, and is very hard and tough. The locality 
is fairly accessible. At Doctor Hill, Mount Rangitoto. and Purcell Ridge solid granite covers 
large areas. The granites of Mount Misery, Fraser Peak, and Bald Hill Range are somewhat 
inaccessible, and often juori- or less crushed or decomposed, probably on account of their 
situation near the great reversed fault of the Alps. 

Much of the limestone of Koiterangi Hill is suitable for building, and more especially 
for monumental purposes. It forms a fine-grained bluish or greyish rock of uniform grain 
and tint, and can be obtained in blocks of considerable size fairly free from flaws. 

Limestones for Agricultural Purposes, etc. 

Some of the Koiterangi limestone is well suited for Ume-maldng purposes, as is shown 
by the analyses given below. In places, however, it contains a rather high percentage of 
silica. At Hodson Creek, near Ross, there is a small deposit of limestone, which appears to 
be of excellent quality (see analysis), and \\-\\\ probably prove of considerable value in the 
future. It has been shown that the application of caustic lime is of the greatest benefit to 
Westland soils, because it liberates the otherwise imavailable potash, of which there is an 
abundance in the soil.f 



* The CO 2 wa.s evolved only on boiling w-ith acid. 

+ See paper by Mr. B. C. Aston (Chief Chemist to Agricultural Department) in "' Report of the Seventh 
Biennial Conference of the Agricultural and Pastoral Associations of New Zealand," 1907, f . 12. 



i5o 



A potential use for limestone is in connection with the manufacture of nitrate of lime (a 
valuable fertiliser) by bringing nitric acid made from air by means of electricity into 
contact with milk of Ume. As is shown in a later section of this chapter, abundant 
water-power is available within ten or twenty miles of the limestone deposits for the produc- 
tion of the electricity required. 

The foUomng analyses of the limestones occurring in the Mikonui area may be of interest. 
Nos. 1, 2, and 3 are from Koiterangi Hill, and No. 4 from Hodson Creek : — 





No. 1. 


No. 2. 


No. 3. 


No. 4. 


Silica (SiOj) 


6-35 


20-91 


16-29 


5-45 


Iron oxides and alumina 










(Fe^Oj and Al^Og) . . 


1-70 


4-29 


2-80 


1-17 


Lime (CaO) 


5010 


40 10 


• 44-27 


51-40 


Magnesia (MgO) 


119 


1-89 


1-59 


0-81 


Carbonic anhydride (CO 2) 


3940 


.32-81* 


35-05* 


39-80 


Organic matter, water and un- 










determined 


1-26 


•• 


•• 


1-.37 



100 00 



10000 



10000 



10000 



Road-metal. 
Abimdance of gravel suitable for road-making purposes is obtainable everywhere through- 
out the lowlands of the IVIikonui Subdi\'isiou. A better though^ more expensive class of road- 
metal is furnished by the brealdng-up of the grauwacke boulders which are generally abundant 
wherever glacial debris is found. There is therefore never any need to go great distances for 
road-making material, or to open up quarries in solid rock. 

Clays. 

The Mikonui Subdivision is rather deficient in clays suitable for economic purposes. 
The carbonaceous clays and shales of the coal-measures in Koiterangi Hill are not adapted 
for use as fireclays. "j" 

Near Ross, and more particularly at McLeod Terrace, there are Upper Miocene blue 
clays wliich are probably suitable for brickmaking, but so far have been utilised only for the 
rather humble purposes of whitening fireplaces, &c. The decomposed granite outcropping 
along the McLeod's Terrace Sluicing Company's water-race, about half a mile from their 
claim, has given rise to some white clay which it was thought might be suitable for chinaware, 
but, as shown by the subjoined analysis (No. 2), it is of little value for this purpose : — 



Analyses. 



Silica (8iO J ) 
Alumina (AljOg) 
Iron- oxides (as FcjOg) 
Lime (CaO) 
Magnesia (MgO) . . 
Organic matter and water 
Moisture at 100° C. 
Carbonic anhydride (COj) 
Alkahs (KjO and Na^O) . 
Undetermined 



No. 1. 


No. 2. 


60-25 


61-20 


22-48 


26-70 


6-72 


1-40 


3.10 


1-30 


1-62 


0-32 


1-43 


2-95 


0-25 


1-05 


0-82 


, , 


■3.33 

) 


4-12 
0-96 



10000 100-00 



* Includes water, organic matter, and undetermined. j BulL No. 1 (New Series), N.Z.G.S., 1906, p. 79. 



151 

No. 1 represents the blue clay from McLeod's Terrace Sluicing Claim. When burnt it 
was light-brown in co'onr. 

No. 2 is the analysis of a white clay from the neighbourhood of the granite outcrop along 
the McLeod's Terrace Sluicing Company's water-race. Concerning it, Dr. Maclaurin re- 
marks, " When burnt this clay was very light-coloured, almost white. It contains mica, 
and lacks plasticity. It is imsuitable for the manufacture of fine pottery owing to the high 
percentage of alkali and the comparatively large amounts of iron-oxides and lime." 

Coal. 

Seams of coal are known to occur in the Mikonui Subdivision only at Koiterangi Hill, but, 

as pointed out m Chapter VIII, there is a patch of coal-measures at Humbug Creek, where 

loose coal of good quality was found. Coal has been reported from an area east of Doctor 

Hill, but no coal-bearing rocks were found in that locality. A thin seam of coaly matter a^so 

occurs in Coal Creek, near Ross. The seams at Koiterangi, which, so far as explored, are rather 

thin, and very impure, were fully described in the Hokitika Bulletin.* It is just possible that 

in places they may be found to ^-ield coal of marketable quality, which could be used locally. 

The upper of the two seams which outcrop south-west of the trigonometrical station is a mere 

band of carbonaceous clay with coaly partings. The lower seam is 6^ ft. thick, with an 18 in. 

band towards the top, of better quality than the lower 5 ft. The analyses of samples from 

this seam given in the Hokitika BuUetui are here appended, together with one of the loose 

coal found in Humbug Creek : — 

Koiterangi Seam. 
Upper 

Fixed carbon 

Hydrocarbons 

Water .. 

Ash 



Total sulphur 507 4-62 1-37 

The Humbug Creek coal burns to a red ash, and when heated in a closed vessel does not 
frit or coke. By a calorimeter test it fields 7,055 calories per gram, equal to 12,699 British 
thermal units per pound. The calculated evaporative power per pound of coal is therefore 
13-14, or. assuming 60 per cent, boiler efficiency, 9-88 lb. of water at boiling-point will be 
converted into steam (at the ordinary atmospheric pressure) by 1 lb. of the fuel. 

AuRiFEROis Alluvial DEPOsirs.f 
These may be considered under the headings of — 
(1.) River and creek gravels. 
(2.) Fluvio-glacial gravels. 
(3.) Beach-sands. 

(4.) Special area — Ross and neighbourhood. 
(5.) Origin of gold-deposits. 

(1.) River and Creek Gravels.— Fine gold can be got in all the larger streams and most of the 
smaller streams within the subdivision by panning off the sand which is entangled with the moss 
growing on the stones near flood-mark. In the Upper Mikonui, the Upper Kakapotahi, and the 
Waitaha, rivers which drain neither the main divide nor areas of Greenland rocks, colours are 
very scarce. The Wanganui River, though draining a considerable extent of the main divide, 

• Bull. Xo. 1 (Xew Series), N.Z.G.S., 1906, p. 79. t See also pp. 22-24. 



ler Portion. 


Lower Portion. 


Humbug Creek. 


30-8 


22-7 


61-85 


37-7 


28-9 


2710 


3-6 


2-9 


710 


27-9 


45-5 


3-95 


1000 


1000 


100-00 



1-52 

does not seem to carry much fine gold, though colours are more common than in the Waitaha 
watershed. The one main river of the area with decidedly auriferous gravels is the Hokitika, 
with which must be included its chief tributary, the Whitcombe. and perhaps also the 
Mungo. 

In the Upper Hokitika Valley, where the gorge east of Conway Ridge begins, good pro- 
spects can be obtained from the gravel in the rock cre\'ices. Were not the locality so remote, 
and at such a high elevation, there is little doubt but that in %vinter time, when the stream is 
low, its bed could be payably worked for a season or two. There is, however, no scope for 
more than one or perhaps, two parties. 

The Mungo, above its junction with the Hokitika, also carries gold, but not in quantity. 
At the bend marked " Gold Point " on the map, a few grains of gold were obtained from the 
crevices by menibers of the Geological Survey parties. Below Gold Point is a small flat which 
is worth prospecting. Lower down the Hokitika. towards the Whitcombe junction, a few 
large specks of gold were obtained on one of the beaches. 

Below the Whitcombe jimction small payable beaches have been worked near Rapid Creek 
and elsewhere. A little gold has also been obtained from the sands deposited in flood-time 
at the Hokitika Gorge where the river emerges on the lowlands. A high gravel terrace near 
Rapid Creek carries a little gold, and the Geological Survey party obtained rather promising 
prospects from the gravels of the high terrace below Hokitika Gorge, on the west side of the 
river. 

The Whitcombe River sands are verj- decidedly gold-bearing. Payable beaches have 
been worked on its western bank opposite Frew Creek and near Vincent Creek, but these 
were exhausted in a short time, and up to the present have not been renewed. From near the 
junction Avith the Hokitika to Price River junction the Geological Survey party washed out 
many good prospects of fine gold from the moss-entangled sands of the river. With these sands 
there is associated a good deal of zircon in small grains, most of which show crystal outlines, 
with little sign of abrasion. On the east side of the river, a little above Cataract Creek, there 
is sufficient auriferous sand to furnish payable results to one or two men for a few days, if 
the actual working-time alone be considered. The ordinary river-sands always yield a colour 
or two, and in places small moderately payable beaches are possibly present. The gravel 
terraces along the ^Miitcombe generally contain colours of gold, but have never been reassorted, 
and are probably nowhere payable, even could water be obtained without expenditure of capital. 

A large amomit of gold has been obtained from the valley of the Totara. a river which 
has nearly its whole course in the area occupied by Greenland rocks. On the west side of 
the river. Fox, Hatter, McKenzie, Cameron, and other creeks draining from the slopes of 
Momit Greenland have given much gold. Cedar Creek, further inland, has not furnished 
any allu\ial gold worth mentioning, notwithstanding the reefs at its head. The same is the 
case with the creeks on the east side of the Totara, which have yielded but little gold, though 
all run through reef -bearing country. There is therefore some reason for suspecting that 
much of the gold in the richer creeks has not been derived from their watersheds. At Totara 
Forks the gravels near the main stream were payably auriferous. ^Vhen the Totara is low, 
experienced or lucky men, Avith a prospecting-dish and a small pick as their whole outfit, can 
often make wages for some miles below Totara Forks bv fossicking in the crevices of the river- 
bed. 

At Ross, where during 1866 and succeeding years such great quantities of gold were 
obtained, the rich gravels of Jones's Flat (Ross Flat) must be ascribed to Donnelly Creek and 
its tributary Jones's Creek, which have reassorted older auriferous gravels. These modern 
gravels, as is well known, extend to 300 ft. or more below sea-level, and are as yet in great 
measure un worked. 

The rich grave's of Sailor Gully, Clear or Donoghue Creek, &c., now long worked our, 
may A^so be ascribed to a concentration of older gravels by the various httie streams which 
traversed them. 



PJ.ATE XXVIII. 



,-4#^ -^ 




Vii;\v FiiOM Mkta I{A\(iE ii- MiNco Vai.i.ky. Molnt Pakk (0.710 it.) on uu.iiT, Bastiox 

Iiiu<;k ('),'.)H> ft.) ox lkkt. 




Head ok Vixx'EXt Ckkek, with Ki;a Pass in distaxce. 
Gtol. /Jul/. Xo. 0.] [To fu<->: ; - /•: 132. 



153 

Redman Creek. Italian Gully, and their branches — streams which drain from Moiuit Green- 
land into the Mikonni River — aIbo owe their formerly rich gravels to a reassortment of older 
material. 

Cameron Creek, a branch of Red Granite Creek, which drains from the north-east slopes 
of Mount Rangitoto, has been worked for gold more than once, but payable wash still remains. 
The difficulties are (he expense of obtaining a high-pressure supply of water, the enormous 
boulders in the wash, and the absence of any track to the loca'ity. The gold-bearing wash 
here consists of granite and grauwacke boulders of all sizes. It has evidently been derived 
from the slopes of Moiuit Rangitoto, and its auriferous character points to the existence of 
one or more gold-bearing quartz lodes within the drainage-area of Cameron Creek. 

The only other auriferous gravels that need be mentioned are those of Duffer Creek. A fair 
amount of gold has been obtained here for distances of about a mile above and below the 
road-crossing, but the creek is now entirely worked out. The gravels above the road-crossing 
are almost entirely derived from the gneissic schists, which therefore appear to have been 
the source of the gold. This conclusion, however, is open to considerable doubt. Below the 
road grauwacke boulders appear, and the gold may have in part a different source. 

(2.) Fluvio-cjlacud Gravels. — At the Mont d'Or Claim, near Ross, the lower part of the 
working-face consists of gravels of various degrees of coarseness, which are perhaps not strictly 
fluvioglacial gravels, but are considered by the writer to have been deposited by streams 
flowing in advance of the Mikonui Glacier. These layers contain practically all the gold, and 
ard capped by other poorly auriferous layers of more, or less morainic material. The 
fluvio-glacial layers consist largely of material derived from the Moutere Gravels which has 
been more or less concentrated by the glacial streams. 

At McLeod's Terrace Sluicing Claim, on the west side of the Mikonui, the gravels are 
exactly similar to those of the lower layers in the Mont d'Or face, except that they seem to 
contain less gold. 

The claim at the north end of Lake lanthe, from wliich gold to the value of £1,700 has 
been obtained, exhibits a face of fluvio-glacial gravels deposited in connection with the 
ancient Wanganui Glacier. The nature of the wash, which consists largely of decomposed 
grauwacke, suggests that it has been in part derived from the old Moutere Gravels, but, 
unfortunately, this point was not considered at the time of the writer's visit, and a positive 
statement cannot be made. 

(3.) Beach-satids. — In the pioneering days various parts of the sea -beach were rich in gold, 
particularly at Donoghue's. near Ross, and the Waitaha Beach for some miles south of Duffer 
Creek. At the present time several men are still employed in working the beaches from Duffer 
Creek to near the Wanganui Bluff, but the returns are not highly remunerative, though occa- 
sionally the miners do well for a few days. 

As stated on a former page, the gold is mvariiibl}' associated with black-sand (titaniferous 
magnetite), as well as with minor amounts of garnet, zircon, and perhaps other heavy minerals. 
The auriferous black-sands appear about high-water mark, but at certain times much more 
abundantly than others. The conditions vary, but a moderate sea following a period of 
heavy weather is generally favourable, although black-sand does not always collect to any 
extent when the conditions seem suitable, nor is it always payably auriferous. 

Though a rich patch of black-sand often makes in a single tide it is evident that the first 
working of the beaches makes a noticeable inroad on the store of gold available, and that a 
rich beach once worked, although likely to form payable patches at any time, would, as a 
rule, need to be left undisturbed for a long time before deposits equal in value to the original 
black-sands would form. 

(-1.) Special Area — Ross and Neighbourhood. — The very large amount of gold which has been 
obtained in the neighbourhood of Ross renders this area of special interest. All the richer gold- 
drifts above sea-level have practically been worked out. There remain only the auriferous 
fluvio-glacial gravels now being worked by the Mont d'Or Company, and small patches of 



154 

river and creek gravels which were too poor to be worked in the early days, but are now 
gradually being disposed of by hydraulic and ground sluicing. 

One of the smaller claims in Bayley Creek, worked by Smith and party, deserves special 
attention, because both wash and gold are of a different character from that usual in the 
neighbourhood. The material being sluiced consists at the surface of non-auriferous creek- 
gravels, underlain by a thin layer of auriferous material consisting of small pieces of broken 
quartz and grauwacke, with some clay and iron-oxide. Then comes a layer of angular grau- 
wacke boulders, which rests upon another auriferous layer 2 ft. thick. This latter consists 
of the same materials as the layer of wash above, but broken quartz is, perhaps, more prominent. 
It rests upon a bottom composed of much-crushed grauwacke. The loose gold is invariablv 
hackly, and has evidently travelled no great distance, whilst the fact that many of the pieces 
of quartz contain \dsib!e gold indicates that a quartz lode is its immediate source. Owing 
to crushing of the lode and the enclosing country by fault -movements, much of the gold has 
been liberated, and washed down the hillside to its present resting-place, along with some of 
the quartz which formed its matrix. The neighbouring grauwacke was apparently so much 
crushed that most of it was washed away, but after the lower layer of wash was formed, a 
quantity of less finely broken rock was washed or perhaps slipped down the hillside over 
the auriferous layer. Then came more auriferous material, and finally the gravels of the 
main creek. 

The cliief gold-bearmg area of the Ross district, Jones or Ross Flat, has already been men- 
tioned several times. It is known to be practically worked out to water-level — that is, about 
sea-level — or 90 ft. below the surface of the upper part of the flat, and a considerable quantity 
of gold has also been obtained below this level. 

Water, or rather the want of adequate pumping appliances, has always prevented the 
lower levels from being continuously worked for more than a few months at a time, and it 
seems doubtful whether the supposed auriferous layers are continuous, or whether the gold 
is merely in patches. 

The only reliable data available to the \vriter are those recorded by S. H. Cox in 1883 and 
1884, and certain information which has been published from time to tune in the Mines Reports 
relating to the Ross United and other deep-level mines.* From these sources of information 
it would appear that doA\ii to the 300 ft. level or thereabouts there were six aui'iferous layers 
worked, of which No. 6, the Cassius layer, was the richest. Towards the head of the flat 
Nos. 4, 5, and 6 were supposed to unite, and form one rich layer resting on the Upper Miocene 
clays and sands, the denuded surface of which sloped rapidly seawards. Layers 1, 2, and 3, 
nearer the surface than the others, were younger and less rich. Towards the head of the flat 
they ran out to the surface, or disappeared. Nos. 2 and 3 were supposed to merge into one 
another before ending. 

The Ross United shaft, 392 ft. deep, is stated to have passed through eight gold-bearing 
layers, the first six of which were supposed to be identical ^\^th those worked in the early claims 
from 1866 to 1872. It seems evident that none of them was extraordinarily rich where passed 
through, but after prospecting in various directions the company struck highly payable wash, 
and for a few months obtained good results, but the inadequate size of the pumps soon brought 
disaster. In 1888 the mine became flooded, and has remained so ever since. 

The bulk of the evidence available and the general opinion of the old miners seem to 
support the view that the auriferous layers are continuous, though varying in gold- content, for 
some distance seaward from the head of the flat. No. 6, or the Cassius layer, being the richest. 
It appears to be certain that there is a considerable amount of unworked payable wash, pro- 
bably in several layers, below the water-level. The ground is likely to be rich only in patches, 
and may become poorer seawards, but from a mining point of view there is ample justification 

*See more particularly the Mines Reports for 1887, pp. 43-44 ; 1899, C.-3, pp. 116-122; and 1907, 
C.-3, p. 8. To this list may be added "The Handbook of New Zealand Mines," 1887, pp. 165-170, 
and "The New Zealand Mining Handbook," 1906, pp. 12-15, 106, 119-120, and 139. 



155 

for an endeavour to work the deeper layers wnth the aid of modern machinery. In view of 
the universal uncertaijity and erratic distribution of auriferous alluvial deposits, little more 
than this can be said. There is, however, the possibility of deeper layers of auriferous gravels 
than those at present known beiiig struck, more particularly towards or on the old Upper 
Miocene surface (sandstone bottom). 

(5.) Origin of Auriferous Alluvial Deposits.— The first impulse on viewing the conditions 
under which the alluvial gold of Westland occurs is to refer its origin to the alpine chain. The 
early miners, acting on this opinion, searched the main rivers to their sources, only to meet 
with almost complete disappointment. The general impression at the present day is that the 
mountains have been very superficially prospected ; but as regards gold, at least, the reverse 
is the case. The geological examination of the Mikonui Subdivision shows that while there is a 
little alluvial gold in the alpine region, and occasional lodes which carry gold, the alpine chain, 
as was pointed out by McKay many years ago, is apparently not competent to supply more 
than a part of the alluvial gold of the lowlands. There is, however, the possibility, and, in 
fact, probability, of the denuded portions of the Alps haviiig been much richer in gold than 
those which remain. When this circumstance is taken ijito account, there might perhaps be 
little difficulty in supposing the Alps to be a competent source of all the alluvial gold found 
in the lowlands, but there are other difficulties to be considered. The first of these is that no 
payable deposits other than small river-beaches are found east of the western boundary of 
the Southern Alps ; another is the payable character of certain fluvio-glacial deposits which 
have apparontlv not been coiicentrated to any extent, whilst other fluvio-glacial gravels are 
almost non-auriferous. Again, there is the difficulty of explaining the concentration 
necessary' to produce the richer layers and patches which were worked in the early days. 

Outstanding facts in coimection with all the richer and more extensive deposits are that 
all occur overlying or near the Upper Miocene deposits known in North Westland as the 
Blue Bottom, and most contain nimierous rotten grauwacke boulders which undoubtedly have 
been derived from the Moutere or Old Man Bottom gravels. 

We may therefore conclude, with McKay,* that the present alpine chain did not supply the 
bulk of the alluvial gold which has been obtained in Northern Westland, and that the Moutere 
Gravels are the immediate source of much the greater part. In Chapter XI it was stated 
that the Moutere Gravels were, in Westland, largely derived from the Koiterangi or coal- 
measure conglomerates, a conclusion also supported by McKay. It is therefore likely that 
much of the alluvial gold was freed from its matrix in Early Tertiary times. In the Late 
Miocene and Early Pliocene the great river which is supposed to have nin north-west from 
Ross not only broke up and concentrated the coal-measure conglomerates, but it is probable 
claimed tribute from the land then in existence to the west, as well as from the rapidly rising 
Southern Alps. Much of the material forming the Moutere Gravels has therefore been re- 
assorted more than once ; but, somewhat strange to say, the portions that survive, though 
in several places worked for gold, are not particularly rich. It must be remembered, how- 
ever, that, so far as known to the writer, they are nowhere exposed in contact with the Blue 
Bottom, where the richer layers might be expected to occur. 

Soon after their deposition the Moutere Gravels were broken up, and their gold-contents 
more or less concentrated by the fluvio-glacial streams, notwithstanding the great amount of 
poorly auriferous debris which the glaciers must have carried. It must be supposed that 
much of this, being coarse, was deposited as lateral and terminal moraine, whilst the subglacial 
streams, concentrating both the Moutere Gravels and the slightly auriferous material froni the 
mountains, delivered gravel approximately equal in value to the original Moutere beds to 
the rivers which flowed from the terminal faces, and i)\ this bulletin are often included with 
the strictly flu\io-glacial streams which flowed upon, within, or underneath the glaciers. At 
any rate, it is certain that much payably auriferous material was deposited immediately in 

♦ For a full exposition of McKay's views, see literature cited on next page. 



156 

front of advancing glaciers. During and after the retreat of the glaciers the fluvio-glacial 
and morainic deposits were further concentrated by the streams, often into very rich deposits. 

This was probably the case at Ross, and in the Totara Valley at Fox Creek, Hatter 
Creek, &c. In both localities auriferous material derived from the slopes of Mount Greenland 
contributed a quota, whilst the Upper Miocene sandstones seem to have formed a suitable 
bottom on which the gold could be concentrated. 

The reader must be referred for further information concerning the origin of the alluvial 
gold in Westland to the reports of McKay, who has ably discussed the subject on several 
occasions.* 

Prospecting. 

Consideration has now to be given to the question of directing prospectors both where 
to look and where not to look for valuable mineral deposits. 

The opinion has already been expressed that the alpine area within the Mikonui Subdivi- 
sion has been sufficiently prospected for gold. There is little likelihood of payable quartz reefs 
being found, and the small patches of auriferous river-beaches in the Hokitika watershed 
can never do more than support a few small parties for short periods at long intervals of 
time. One or two likely terraces which might }deld some gold if water were available have 
prc\-iously been indicated. In the horizon of the Pounamu Formation there are occurrences 
of copper-ore which sometimes carries a little gold, silver, and platinum. The writer does 
not consider that the expense of systematic prospecting for copper in such rugged country 
would be justified, but there are slight possibilities, aiid chance may sometime reveal a work- 
able deposit. Persons who have other reasons for visiting the neighbourhood of the serpentine 
outcrops would therefore do well to be on the outlook for payable deposits of the minerals 
known to occuj, but more especially for copper-ore. 

Though asbestos of fine quality occurs in connection with the serpentine outcrops, it has 
only been foimd in small scattered pockets, iind this, together with the diffirulty of access, does 
not seem to hold out any great probability of really payable material being discovered. 

Much the same remarks apply to the finer grades of talc. Here the cost of transport 
practically destroys any hope of the material yielding any scope for mining imder presBnt 
conditions. 

The possible occuiTence of rubies in the matrix in or near the Pomiamu Formation is of 
interest, and may perhaps justify considerable prospecting. It must be borne in mind, how- 
ever, that the supposed association has not yet been proved to exist. 

On the whole, then, systematic prospecting in this portion of the Southern Alps has but 
a limited scope. There is no auriferous belt within the Mikonui Subdivision, but the horizon 
of the Pounamu Formation, with its copper, gold, silver, platinum, chromium, asbestos, talc, 
rubies, &c., offers as a whole a rather tempting area for the prospector, though it is one that 
the writer recommends to the born prospector and enthusiast rather than to the mere utili- 
tarian. 

In the foothill area it is principally on Mount Greenland and the neighbouring ridges 
that the search for payable auriferous lodes is likely to be rewarded, but the slopes of Mount 
Rangitoto, especially near the grauwacke-granite contact, deserve some attention. The lode 
prospected by the old Rangitoto Silver-mining Company has possibilities in gold rather 
than silver. There is probably at least a little payably auriferous wash on the north-eastern 
slope of Rangitoto, in the neighbourhood of Cameron Creek, where also a search for auriferous 
quartz lodes seems justifiable. 



* " Geological Explorations of the Northern Part of Westland," Mines Report, 1893, C.-3, pp. 174-182. 
— " On the Geology of the Northern Part of Westland," Rep. G.S. during 1892-3, vol. xxii, 1894, pp. 19-43. 
— " Gold Deposits of New Zealand " (Reprinted from New Zealand Mines Record), 1903, pp. 38-45. See 
also Gordon, H. A., and McKay, A. : " Mining Reserves, Westland and Nelson," Mines Report, 1896, G.-9. 
pp. 2-6. 



167 

The patches of coal-measures among the foothills have little or no oommercial value. 
The discovery of small areas of workable coal is possible, but is one that may be left to the 
next generation without any great fear of loss to the present. 

Coming to the lowlands, we find that only alluvial gold offers any s<-.ope to the prospector. 
The surface of the lowlands, however, has been searched over and over again, and any payable 
deposits exploited almost to the uttermost. There remain to be considered the deep leads 
near Ross, and other possible occurrences of sijnilar nature. A favourable opinion concerning 
the Ross Flat has already been expressed. 

Th(> (H-currcnco of Moutcrc Gravels neaj- Ross leads the writer to think they are worth 
prospecting, not b>- adits, but by boring or by shaft-sinking. Any rich' layers in these gravels 
are probably near or on the sandstone bottom, and therefore boreholes or shafts would need 
to bo of considerable depth. The sinking of shafts and the driving of prospecting levels would 
be expensive work, especially when the cost of pumping is considered. If, however, the drainage 
of Ross Flat is accomplished, the pumping, or any other shaft on the flat, would serve as a 
suitable starting-point for prospecting levels, which might be extended far to the north-east 
under the older gravels of the Cemeten,- HiU, &c. There is also the likelihood of a deep shaft 
on the flat entering and finally passing through Moutere Gravels to the sandstone bottom. 
The possibilities of s>-stematic exploration on or near the sandstone (Upper Miocene) 
bottom near Ross are very great. The great difficulties will be water and the complications 
caused by the extensive faultiiig which has gone on in the district. Probably, therefore, 
it is only in conjunction with the working of the Ross Flat that the expeiise of prospecting 
by deep-level drives is advisable. 

As regards boring operations, these are also likely to be expensive, and in almost any 
case inconclusive unless conducted on an extended scale. If rich ground were struck there 
would be little guarantee that it was of any extent, whilst even if several bores were put down, 
the probability of drawing a blank is at least equal to that of a prize. 

Boring may be rccomjuendcd only for the pxirposc of locating the extension northward 
or southward of the Moutere Gravels when these have been proved to contain really payable 
layers. 

The area of coastal plain between the Mikonui and Totara rivers may contain not 
only an extension of the Ross Flat deep leads, but also auriferous layers belonging to the Older 
Pliocene gravels. 

South of Ross and the Mikonui River is a large area covered with morainic deposits 
and recent gravels which are poorly auriferous, and, though they have yielded gold at a few 
points, have not proved rich. 

The best indications are at McLeod's Terrace Sluicing Claim, where, however, returns 
have so far been extremely disappointing. Notwithstanding this, further trial of the locality 
seems desirable. If the Moutere Gravels and the Miocene sandstones underlie the area west 
and south of the Mikonui there are possibilities in this direction. That Moutere Gravels once 
existed in this locality, and have been perhaps only partly destroyed, is shown by the presence 
of masses of decomposed gravel in the moraij\ic debris of the neighbourhood. 

North of the Totara to the Hokitika River is a considerable area of country overwhelmed 
by morainic debris. Only a small portion is within the Mikonui Subdivision, but this shares 
the potentialities of the whole area. This district was once covered with Moutere Gravels, which 
over'ay the Upper Miocene sandstones, &c., and, lying as it does between two of the richest 
districts in Westland, must sometime receive attention. Concerning it McKay has written , 
" In my opinion there is a vast field between the Lower Hokitika and Ross over which auri- 
ferous river-gravels may be found underlying the superficial glacier deposits. It cannot be 
doubted, however, that the prospecting of such ground will prove a costly and perhaps not 
always a remunerative undertaking."* With McKay's conclusions the wi'iter agrees. 

* " On the Kumara Gold Drifts," (i..S. Rep. during 1892-.3, vol. xxii, 189i, p. II. 



158 

It is advisable, however, to point out that the ground caimot be efficiently prospected 
by haphazard shafts or drives. Its possibilities will be best ascertained by working from 
the known to the unknown — that is, deep workings miist first be inaugurated in the localitiet- 
where gold has already been obtained in quantity. 

If the working of the deep levels at Ross should prove unsuccessful, the expense of pro 
specting the other areas carrying possible deep leads in the vicinity would probably not be 
justified. On the other hand, if a payable mine is developed in this area, it at once increases 
the potentialities of neighbouring ground, and provides a convenient base for prospecting 
operations. 

The rock-basins which have been formed in the river valleys of the foothill area by 
tilting (see page 74) may possibly contain buried leads of auriferous gravel but at the 
present time the evidence in favour of this view is too slender to justify prospecting by boring 
or otherwise. 

WATER-POWEft. 

An age is approaching when the coal- deposits of the world will in part be exhausted, in 
part more difficult and expensive to work than those being exploited at the present time. 
Mankind will then have to rely very largely upon water as a source of power, and industrial 
centres will spring up wathin easy reach of districts where it is available. Modern science 
has rendered the transmission of water-power by conversion into electricity so simple a matter 
that a feat deemed impossible sixty or seventy years ago is now accepted as a matter of 
course. 

In respect to water-power Westland is richly gifted. The great gold placers have largely 
been worked out ; fifty to a hundred years will see the bulk of its timber resources tapped, 
but its water-power will endure as long as the Alps rear their lofty summits to claim tribute 
from the moisture-laden westerlies. Even at the present time there are no mean possibilities 
connected with the Westland water-powers conjoined with electric transmission. There 
are deep leads to be exhausted of water ; there are other auriferous deposits which could be 
profitably worked by hydraulic sluicing if power were available to create artificial pressure ; 
there are railways and sawmills which could be conveniently run by hydro-electric energy. 

It may be said that there is hardly a stream in the Mikonui Subdivision which is not 
capable of yielding a respectable amount of power under circumstances which would enable it 
to be profitably utilised if an industrial centre were within a few miles. 

In the followng paragraphs the more obvious sources of water-power in the subdivision 
will be indicated, and in some cases calculations of the horse-power available will be 
supplied. 

Taking the principal streams in order from north to south, the first to be considered is 
the Kokatahi. In the upper part of its course considerable power could be obtained from 
this river and its tributaries, such as the Clarke, Crawford, &c. Lower down there is a iiote- 
worthv drop at the Whakarira Gorge, which was not exactly ascertained, but is probably 
500 ft. or more in about two miles, if measured in a straight line. Compared with the Toaroha 
Canvon, presently to be mentioned, this gorge would fujnish about the same amount of power, 
but probably at a considerably greater cost. Adamson and Hawk creeks, which descend 
in cascades and falls from the slopes of " The Pinnacle," are each capable of furnishing several 
hundred horse-power when in normal conditioii. This could be cheaply developed in each case, 
but there would be no storage, and since the streams are not permanently snow-fed, they 
would occasionally run very low in summer weather. 

The remarkable cascade of the Upper Toaroha, where the drop is about 500 ft. in half 
a mile, would on occasion f Ornish some thousands of horse-power, except for short j)eriods 
in dry autumn seasons when there is not much snow within th'^ Toaroha watershed. Crystal 
Creek, which joins towards the foot of the cascade, is permanently snow-fed from the slopes 
of Mount Chamberlin, and its falls would probably furnish 500-horse power all the year 



159 

round. MuUins Creek and several other tributaries of the Toaroha may also be expected 
to furnish a considerable amount of power. 

It is, however, at Toaroha Canyon that a most attractive water-power scheme presents 
itself, air. R. P. Greville, Departmental Topographer, was the fixst to call attention to the 
possibilities of this locality. These have also been pointed out in departmental reports* 
and in the public press. In less than three-quarters of a mile, measured in a straight line, 
the fall is fully 750 ft. The mean of three measurements made by officers of the Survey of the 
stream- volume at Cedar Flat, just above the gorge, is 377 cubic feet per second. The ordinary 
minimum flow is estimated at 200 cubic feet per second, and in exceptional seasons, such 
as come once in ten or fifteen years, it may fall to perhaps 150 cubic feet per second. 

The minimiun flow, with, say, twelve to twenty-four hours' storage, could be very cheaply 
utilised by building a timber dam just above the canyon, where there is rock on one side of 
the river and a steep debris bank on the other. Probably solid rock would be found here 
at a very moderate depth, and also at no great distance within the debris slope. A high concrete 
dam, gravel for which is available in the vicinity, would, of course, cost a large sum of money, 
but would probably enable over a fortnight's supply of water to be stored. Water could 
be led away by means of a tunnel about half a mile long into the Lower Toaroha Valley. Taking 
the mininium flow at 200 cubic feet per second, a simple calculation shows that for a twenty- 
four-hours scheme energy equal to 17,000-horse power is available, and might be relied upon 
to produce nearly 12,000 -horse power when converted into electricity .f From the 
extreme mininuni flow of 150 cubic feet per second 9,000 electrical horse-power would be 
evolved. With storage a minimum flow of 250 cubic feet per second, yielding at least 
15,000 electrical horse-power, might be expected. For a twelve-hours scheme double this 
quantity of energy cohld be developed, and this at a point within a short distance of the low- 
lands, and not more than seventeen or eighteen miles from Hokitika. 






^w 



h\ „o 
















^-^^^^v^ 


\0 
















st/ 


~T 


1 
1 
1 

1 




1 
-. . 1 


c?° .^ 




1 1 

1 1 


1 



_fc 



/Om 35c. 



Diaqram 



showing profile of Toaroha 

SCALES 



River 



HORIZONTAL 



Since the announcement of the power possibilities of the Toaroha Canyon some doubt 
has been cast upon its value at seasons of minimum flow. This can only be conclusively 
settled by observations of the stream- volume during dry weather for a period of not less than 
twelve months. A calculation based upon a run-off of 200 in. per annum and a drainage- 
area of 19 square miles shows that the average flow will be 280 cubic feet per second. This 
would mean a possible minimum flow of little more than 100 cubic feet per second, and there- 
fore to some extent supports the doubts raised ; but, nevertheless, the writer prefers for the 
present to stand by the figures already given. An overestimate at the present time can do 
no harm, for in any case stream-measurements extending over a period of a year ought to be 
undertaken before any power scheme is begun. 



• Annual Report of the Geological Survey Department in Mines Report, 1906, C.-3, p. 129 ; and First 
Annual Report (New Series), 1907, p. 16. 

t The combined efficiency of water-motor and dynamo is assumed to be about 70 per cent. In practice 
a slightly higher figure ought to be obtained. 



160 

The equalising effects of springs, of heavy bush, and of melting snow ought to be 
remembered as tending to raise the minimum flow of the Toaroha and other Westland rivers 
above what might ordinarily be expected. 

The Upper Toaroha watershed is all in the belt of maximum precipitation, ajid it would 
not be particularly surprising if the aimual run- off amounted to fully 250 inches. 

The Upper Hokitika, before entering the Mungo, falls nearly 1,400 ft. in little over a mile, 
and could yield a fair amount of power. In winter, however, it becomes very low. The rather 
flat upper valley has some storage- capacity. The Hokitika from the Mungo to the ^Vhitcomba 
junction has a fall of over 100 ft. to the mile, and could, if required, supply a large amount 
of energy. 

The Whitcombe River, from the Wilkinson junction downwards, has a fall of fully 200 ft. 
per mile for a distance of four miles. Below that its fall is over 100 ft. per mile for six or 
seven miles. In all, the liver falls nearly 1,700 ft. in a distance of ten miles if measured along 
the general line of the river, or alaout twelve miles folloAving the minor bends. The ordinary 
flow of the combined Whitcombe and Wilkinson is probably over 500 cubic feet per second, 
and the minimum may be estimated at 200 cubic feet per second, if not more. This amount 
of water would supply over 38,000-horse power, or, making allowances for various unavoid 
able losses, something like 25,000 electrical horse-power. The energy from this scheme could 
be augmented by power from the Whitcombe above the Wilkinson junction, the Wilkinson 
itself, Price River, Vincent Creek, Cropp River (a large amount of power could be supplied by 
this stream), and other tributaries. Moreover, further power could be obtained from the main 
stream by picking iip its water at suitable points. Fifty thousand electrical horse-power 
is an underestimate of the total amount of energy available, but the development of it would 
be an extremely expensive matter. For a small scheme the Cropp River offers the best possi- 
bilities, and might be relied upon for fully 10,000 electrical horse-power, except during short 
periods of nmiiinxun flow. Though twelve to twenty-foui' hours' storage might be obtained 
economically, the upper hanging valley is not flat enough to afford any great storage except 
by very expensive dams. 

The falls of the Upper Mikonui, and of its tributary the Dickson, may be estimated as 
capable of yielding some hundreds of horse-power within twelve miles of Ross. Consider- 
ably greater power could be obtained from the Mikonui's main tributary, the Tuke, at a point 
still nearer Ross. By damming the whole Mikonui at the lower end of Gribben Flat, and con- 
ducting its waters a distance of four or five miles through the gorge below, 5,000 or 6,000 
electrical horse-power could be obtained at a point not far from Ross, but the scheme would 
be a very costly one. 

The Kakapotahi could be easily dammed at the lower end of Happy Valley. By a tunnel 
into the YVaitaha Valley, somewhat over a mile in length, a fall of nearly 500 ft. would be 
obtained. This, with the minimum flow of about 80 cubic feet per second would give over 
4,500 gross horse-power, or about 3,150 electrical horse-power at a point some ten or twelve 
miles from Ross. Unde.- this scheme there would be difficulty in disposing of the waste 
water, and it might be preferable to convey the water by tunnels and flumes down the 
Kakapotahi Valley. 

The Waitaha is a river which is capable of furnishing an immense amount of power. 
In the mile and a half above County River junction the fall is not less than 1,500 ft. The 
ordinary minimum flow is certainly above 100 cubic feet per second, so that the stream might 
yield about 17,000 gross horse-power. From County River junction to the Kensington Flat 
the drop is over 1,100 ft. in four or five miles, and the minimum volume probably about 
250 cubic feet per second. Again, from Kensington Flat to a short distance below the out- 
let of the gorge below there is a drop of over 270 ft. in little over half a mile (measured in a 
straight line). The measured volume of the whole river when in a low summer stage above 
the gorge was 797 cubic feet per second, with an estimated minimum flow during winter of 
Qot less than 350 cubic feet per second. The total gross horse-power that can be obtained from 



PLATE XXIX. 




■'^«!ft? 




View i.ookim: South fhom Ckdau Vj.at to Hi;ad of Toahoiia. Mount Itoss j.\ backc; 



HOUND. 




O.MATANE Canyon, Uppek Hokitika Kiver. 



Gcol. Dull. Xo. 6'.] 



[To face, yuijt IGO. 



162 

In the foothill area the slopes of Mount Greenland and Rangitoto decidedly warrant a 
little further prospecting for gold-bearing lodes. 

Coming to alluvial gold, it is thought that occasionally a little may be obtained in the 
Hokitika and Whitcombe valleys from the river beds or beaches. Possibly also one or two 
of the terraces might be worked, and yield sufficient gold to pay wages, but there is practically 
no likelihood of a rich deposit. In the foothill country there is some alluvial ground yet un- 
worked though not untried on the eastern slopes of Rangitoto, and possibly there are small 
patches among the morainic gravels similar to those worked on Whaleback Hill and near 
Lake lanthe. 

The sea-beaches also will yield from time to time a recurring but probably ever smaller 
crop of fuie gold. , 

The one great mining potentiality of the district is the deep auriferous grourd of Ross 
Flat. The particular lead formerly worked by the Cassius, Morning Star, ExceUior. and 
Ross United claims may have a considerable extension seaward, and there are possibilities 
of others. 

There is, further, a fairly good prospect of rich leads occurring in the hitherto untested 
portions of the Moutere Gravels (Old Man Bottom) wbich outcrop near Ross over small areas. 
It is suggested that these gravels or concentrated material from them may be found beneath the 
morainic deposits north of the Totara and south of the Mikonui as well as between these 
two streams. A recommendation is made that as much ground as possible should be tested 
from any deep workings which may in the future exist on Ross Flat, for otherwise it is 
feared that the expense of systematic prospecting in what is practically an xmtried area will 
be too great. Finally the writer would say this : At and near Ross Flat there is a brilliant 
pos ibility ; but to test its value will require much skill and judgment, and the unavoidable 
expenditure of la ge sums of money. 

As regards water-power, there is every reason for hoping that in time to come it will 
bring a prosperity to Westland equal to that of the mining industiy in its best days, and 
incomparably more permanent in its nature. 



1G3 



APPENDIX. 



List of Minerals found in the Subdivision, Mode of Occurrence, and Chief 

Localities. 



Minerals. 



Mode of Occurrence. 



Chief Localities, &c. 



Gold 
saver 



Platinum . . 
Copper 

Galena 
Pyrite 

Pyrrhotite 

Hxmatite 
Limonitc . . 
Magnetite 

Titanium . . 

Ilnienit(> 

RuHii- 

Titanite or sphene 

Manganese 

Rhodonite 

Manganese-oxides 

Chromium 

Chromite . . 

Quartz 

Rubv 



Olivine 
Serpentine 
Antigorite. . 
Bowenite . . 
Talc 



Augite 
Hornblende 



Actinolite 
Tremolite 



In lodes and alluvial deposits as the native metal 
In quartz and pvTitic lodes. Form unknown. 

Constitutes a few per cent, of alluvial and 

reef gold 
In quartz and pyritic lodes. Form unknown 

In quartz and pyritio lodes, as sulphide, &c. ; 
also as carbonate (malachite) ; and possibly 
as silicate (chrysocoUa) 

In pj'ritic quartz lodes 

Forms main part of some lodes. Common in 
quartz lodes and as a constituent of many 
altered rocks. Often in fine cubes 

A possible rock constituent not clearly identi- 
fied " : 

.As alteration-products, &c. . . 

Common rock constituent, es])ecially associ- ' 
atcd witli Pounamu Formation. Frequent in 
river and beacli sands. Often titaniferous 

Is present in all rocks of subdivision,* especially 
the basic dykes. 

Pre-ipnt in many rocks, es]>ecially gneisses and 
dyke rocks. 

As a rook constituent. Occurs more especially 
as sagenitic webs*in biotite of granitee . and 
gneisses. 

Common in gneisses as a secondary ))roduct 
(leucoxcne). Occurs also as a minor con- 
stituent of granites. 

Present in minor amounts in most rocks of sub- 
division. 

Found a.s loose boulders 

Found encrusting rhodonite 

Occurs in all rocks of the Pounamu Formation; 
also in talc-schists and in basic dykes. 

In .serpentine-dunite in small grains associated 
with magnetite 

In lodes and as rock constituent 



A.ssociated with su)iposed chrome mica 



As constituent of serpentine-dunite 
As rock masses, &c. 
A variety of serpentine 
A hard variety of serpentine 
As ma.ssive rock, pure crystallized material, as 
talc-serpentine rock, as talc-schi.st, &c. 



As a rock constitneirt — often altered to uralite 
A common rock constituent, often uralitic 



Often with rocks of Pounamu Formation, and 
not infrequently with talc. Sometimes in 
fibrous masses in serpentine 



Throughout subdivision. 
Pounamu Formation, Mount Rangi- 
toto. 

Associated with Pounamu Forma- 
tion and neighbourhood. 

Middle belt of schists from Koka- 
tahi Gorge to Whitcombe River, 
associated more especially with 
Pounamu Formation. 

Near Ross, Mount Rangitoto. 

Associated especially witii Pounamu 
Formation. 

In olivine-diorite of Mount Misery. 

Of common occurrence in small 
' quantity. 
In fine octahedrons at Whakarira 

Gorge, slopes of Mount Bowen, 

&c. 



Hokitika River. 



Mount Bowen. 



Throughout subdivision. Rose 
quartz at Duffer Creek ; ro<^k 
crystal in Whitcombe Valley and 
on many mountain-tops. 

Probably Cropj) River (not found 
in .?!/«). In loose boulders at 
Rimu, Kanieri, &c. 

Slopes of Mount Bowen. 

Pounamu Formation. 

Slopes of Mount Bowtn. 

Mount .Jumbletop. 

Horizon of middle schiacs from 
Kokatahi to Waitaha River, and 
more especially Pounamu Forma- 
tion. 

In dyke rocks ; also in gneisses, &c. 

In syenitic gnei.sses, certain schists 
associated with the Pounamu 
Formation, in many basic dykes. 

Horizon of middle schists through- 
out subdivision. 



Pounaum rocks possibly excepted. 



164 



List of Minerals found in the Subdivision, Mode of Occurrence, and Chief 

Localities — continued. 



Minerals. 



Mode of Occurrence. 



Asbestos . . 
Nephrite . . 

Wollastonite 
Muscovite . . 

Biotite 

F u c h s i t e (chrome 

mica) 
Orthoclase 
Microcline . . 
Albite 
Oligoclase 

Andesine . . 
Labradorite 

Zircon 

Garnet 

Tourmaline 

Apatite 

Calcite 



Dolomite and magne- 

site 
Epidot« 



Zoisite 
Clinozoisite 

Minerals of chlorite 
group 

Glauconite 

Sulphur 
Coal 



Chief Localities, 4c. 



In small pockets and veins in serpentine, &c. . . 

In small masses, associated with Pounamu 
Formation 



As a metamorjjhic product in some scliists. 
Not clearly identified. 

As a con.stituent of granite, gneisses, and some- 
times of schists. Not often plentiful 



Very common constituent of granites, gneisses, 

schists, and some basic dykes. 
Associated witli ru 

tain 
As a cou-stituent of granite. 



Identification not cer- 



Occurs in granites, gneisses, and dark schists, 

and probably also in some quartz-mica- 

.schists. 
May occur in dark schists, also in basic dykes. 
In some basic dykes, possibly also in some 

dioritic gneisses. 
As a minor constituent of granites, gneisses, 

and schists ; also in river-sands 
As a constituent of gneisses and schists ; also 

in river and sea sands 

In some gneissic schists, &c. 

A minor rock constituent seen in granites, 
gneisses, and basic dykes. 

As limestone, in veins and masses associated 
with Pounamu Formation, alteration - pro- 
duct, &c. 

In smaU veins and masses in serpentine 

A common alteration-product. Forms masses 
in association with actinolite and quartz 

An alteration- product not certainly identified. 
An alteration-product 

Massive in association with Pounamu Forma- 
tion. Occur also in clilorite quartz-schist, 
and as alteration-product of biotitic rocks 

In grains in limestones and calcareous rocks. 
.Supposed to represent Foraminifera, &c. 

In small amount in connection with liot springs 

In rather impure seams 



Mounts Jumbletop, Inframeta, and 
Bowen. 

Not found in situ. Loose boulders 
ratiier common in Hokitika 
River, from Whitcombe junction 
to granite gorge. Boulders also 
seen in Toaroha River. 



In rather large plates on east side 
of Mount Misery, and near Wai- 
taha Sugarloaf. 



Not found in situ. 
Mount Rangitoto. 



Sands of Whitcombe River. 

Especially common in belt near 
boundary of^mica-schists and 
dark schists. 

Near Waitaha Sugarloaf ; Tourma- 
line Creek ; Duffer Creek. 



Koiterangi HUl, Hodson Creek. 



Jumbletop, &c. 

Massive in connection with Pov. 
namu Formation at Mount In 
franieta and elsewhere. 

Seems fairly common in granites 

gneisses, &c. 
Whakarira Gorge, Jumbletop. 



Wren Creek (Toaroha Hot Spring). 
Koiterangi HUI, Humbug Creek 
(not found in situ) ; Ross. 



165 



INDEX 



Acidic igneous rocks. 

„ dykes 
Acknowledgments 
Actinolite 



A. 

Page 
See Tuhua Formation. 

..82, 131, 133 
3 
83, 85, 120, 122, 123, 127 



See South- 



. 9-11 
. 10, 12 

10 
00, 13!) 



Actinolite-talc and -epidote rocks . . 123 

Adams Glacier . . . . . . . . 53, 60 

„ River . . . . . . . . 53 

Agriculture and grazing . . . . 11, 12, 29 

Akeake . . . . 8, 9, 10 

Albite as rock-constituent . . 111. 133, 134 

Albite twinning in feldsjiars 81, 86 et seq., 140 

Albite-oligoolase . . 133 

Alexander Creek, alluvial gold of . . . . 24 

Algae .. .. .. 11, 62, 109. Ill 

Allen, Mount . . . . 40, 66, 67 

„ ,, faidt-movement and slip at ..66,67 

Alluvial claims . . . . 24—25, 153 el seq. 

,. method of working . . 24-25 

Alluvial gold, &c. 20. 22 el seq., 143. 151 et seq., 162 
Alluvial mining industry. . .. ..22-25 

(iSee also Alluvial gold, &c.) 
Alpha Company, claim of 
Alpine chain, Alpine divide, .Alps. 

era Alps. 
Al)iiiie and .subalpine Hora 
nieadowland 

scrub, dense character of 
.Alteration of rocks 

{See also Epidotizatiou. Metainorphisni. 
Silicification, &c. ) 
.Miniiina (lossibly acting an acid i)art . . 139 

Ambrose. Mount .. .. ..39.48 

America, South, possible land-connection with 

6. 7, 8, 9 

Amphibole as rock-constituent 81, 83, 85 et seq., 

99, 120, 123, 127, 128, 133, 136 

,, -quartz schists .. ..84,85 

Analyses of rocks and minerals 95, 101, 125, 126, 
127, 135. 141, 148, 149, 150, 151 
(See also Assay.s.) 
Anastomosing of streams 
Anderson Creek, rocks of 
Andesine as rock-constituent 
-Andesitic rocks 
Andrews, E. C. . . 
Animal life. See Fainia. 
Aniseed 
Ankerite 

Annelid, fossil . . 
Anomite 

Anticlinorium of Alps, sup[X)sed 
Antigorite and ahtigoritic rocks 



47, 48, 49, 53. &c. 

133, 1.35-6 

82, 88, 91, 92, 93 

82, 91, 92 

5.-). 131 



30. 



10 

120 

76. 80 

. . 140 

. . 36. 44 

122, 125, 126, 

129 (note) 

,, derived from olivine . . 129 (note) 

Apatite as rock-constituent 82, 86 et seq., 133, 

134, 135, 136, 139 
Aplite and aplitic granite . . 1.30. 132 

Aqueo-igneous action . . . . 131 

Arahura Glacier, ancient . . . . . . 50 

„ River, bend in course of . . 74 

Arahura Series 30-31, 32, 34, 76-95, 14:i-144 

„ age of . . . . 31, 76-77 

,, analyses of rocks of . . 9o 

argillites of . . 30. 76. 85 

12 — Mikonui. 



Arahura Seiies, auriferous rocks and lodes of 

143-144, 156, 161 
,, causes of metamorphism of 79 

„ correlation of . . . . 76-77 

,, derivation of sediments of ..32,85 

„ dip and strike of . . 30, 71. 78 

„ distribution of . . . . 77 

faults of . . 30, 68-70, 71-72 

foldings of 30, 34, 43, 44, 71, 77, 
78, 79 

fossils of . . . . 30, 79-80 

„ general petrology of . . 80-85 

gneisses of 30, 76, 80-82, 86-91 

grauwackes of 30, 76, 85, 94^95 

,, metalliferous veins of 14,3-144 

,, period of metamorphism of 78-79 

„ quartzites of . . . . 30, 85 

„ relation of, to -Greenland 

Series . . . . . . 97 

schists of 30, 76, 80-85, 86-94 

,, special petrology of ..86-94 

,, subdivisions of . . 76, 77-78 

,, structure of . . . . 78 

thickness of 



Area described 
Argillites 
Arthropoda 
Arthur Lake 



. . 79 
. . 1-2 

30, 31, 76, 85, 96, 98, 99 

7 

.. 64 

..116 



,, morauie near 

Asbestos . . . . 120, 122, 126, 147-8, 156 

Assays for gold and other metals 26, 143, 144, 145, 

146, 147 
Augite as rock-constituent 93, 122, 125, 141 

Augite-camptonites . . . . . . 139 

,, -porjjhyrites . . . . . . 139 

Auriferous alluvial deposits 22-25, 26-28, 151-156, 

157, 162 
„ ,, origin of 155-156 

Auriferous alluvial deposits, reassortment and 
concentration of 34, 113, 114, 152, 153, 155, 

156, 162 
Auriferous alluvial deposits, special area of 153-155 
Auriferous belt . . . . . . 143, 161 

Auriferous-quartz lodes and mining 25-26, 143-147, 

156, 161, 162 
Australia, possible land-connection with 6, 7, 34 
Avalanches .. .. .. ..59,60 



R. 

Bald Hill and Range 

„ ,, rocks of 

Barron Canyon 

,, Glacier . . 
Bartrum, J. A. . . 
Basalt 
Basic dykes 

(See also Basic igneous rocks 
Basic igneous rocks 

„ „ age of 

,, ,, alteration of 

„ „ analyses of 

., „ correlation of 



41,51 

. . 109, 132, 149 

. . 48 

48, 59 

1 

. . 138, 139, 141 

30, 82, 138 et seq. 

) 
30, 82, 138-142 
138-139 
.. 139 
141-142 
138-139 



166 



Page 
Basic Igneous rocks, distribution of . . 138 

„ „ mode of occurrence of 

30, 82, 138 
„ petrology of . . 139-141 

,, ,, width, strike, and dip of 

basic dykes included in 138 
Bat, long-tailed . . . . . . 3 

Bather, F. A. . . . . . . . . 80 

Batteries, quartz-crushing . . 25, 26 

Bayley Creek, fault at . . . . 71, 154 

„ mining claims and quartz veins 

in . . . . 25, 145, 154 

Miocene rocks of .. 107,108,110 



C'akite replacing feldspar or quartz 



Beach, sea 

Beach-sands, auriferous . . 

Bealey, rainfall at 
Beaumont, Mount 
Bedded quartz veins 
Beech, white, black, &c. . . 
Beech and rata forest zone 
BeU, J. M. 

Bell- bird or makomako . . 
Bickerton, A. W. 
Biotite as rock-constituent 



. . 15, 22, 65-66 

23, 24, 25, 27, 119, 

153, 162 

13, 14, 15 

40, 61 

143, 144, 145, 146 

. . 8, 9 

. . 8, 9 

1, 12, 18 

4 

. . 147 

81, 83, 85 et seq.. 



99, 100, 109, 111, 124, 127, 128, 132 etseq., 140 



Biotite, formation of 

Biotite-graiiite . . 

Birch, red, white, or black 

Bird-life 

Bittern 

Black-j)ine or matai 

Black-sands, auriferous . . 

,, ,, formation of 

Blight-bu-d 

Block mountain 

Bloomfield Range 

Blue Bottom . . 32, 35, 96, 107, 
,, ice-striated stones of 

„ Pounamu pebbles in . . 

(See also Upper Miocene beds.) 

Bold Head, morainic material of, &c. 



98 

130, 133, 134 

.. 8,9 

.. 4-6 

6 

8 29 

23, 24, 25, 27, 'l53 

153 

4 

41,70 

.. 40 

114, 121, 155 

.. 35 



121 



Bonar, Mount 



15, 22, 42, 65, 
66, 117 
41, 71, 72 
rocks of . . 77, 82, 95, 132, 136, 138 
Bonney, T. G. . . . . 123, 129 (footnotes) 

Boring conditionally recommended . . 157 

Bosses, granite . . ' 30, 31, 43, 71, 77, 97, 130 

Bo'sun Creek, rocks of . . . . . . 92 

Bowen, Mount . . . . . . 40, 61 

,, „ rocks and minerals of 94, 122, 123, 

125-127, 148, 149 
Bowenite . . . . . . . . 124 

Bracken Suowfield . . . . 59, 61 

Breaks, stratigraphical . . . . . . 31 

[See also Uncomf ormities. ) 
Broadleaf . . . . . . . . 8, 9 

Brow Creek, talc-schist in . . . . 84 

Bro\niing Range . . . . . . 39 

Browning or Stj'x River . . . . 39, 47, 50 

Brunswick Creek, hot and cold springs near 62, 63 
Bullock Creek, quartz veins in . . . . 146 

Bunker Hills . . . . . . . . 42 

Bush . . . . . . 7, 8, 9, 28, 29, 160 

„ zone of heavy mixed . . . . 8 

Bush-lawyer . . . . . . . . 8 

Buttercup, mountain- . . . . 9, 10 



Cabbage-tree, or ti . . . . . . 9 

Cabbage, mountain-, or toi . . . . 9 

Calcite as rock- constituent 82, 87, 89, 91, 92, 93, 

98, 99, 105, 106, 109, 110, 111, 

120, 122, 136, 139, 140, &c. 



I'age 

105, 106, 111, 

112, &c. 

41, 70 

24, 153 

3 

..139 

80, 85, 95, 116, 138 



Camelback, or Koiterangi Hill 

Cameron Creek, gold in, . . 

Camps occupied 

Camptonites 

Canterbury, rocks of, &c. 

Canyons. iS'ee (iorges. 

Carboniferous rocks . . . . 25, 31 

(Ste also Arahura Series, Greenland Series.) 
Carmichaelia . . . . . . . . 8 

Carlsbad twinning in feldspars 81, 87, 89, 92, 100, 

141, &c. 
Carpet or hassock grass . . . . . . 10 

Carrot, mountain- . . . . 10, 12 

Cassius, shaft and claim of . . 26, 162 

Cassius layer (Ross Flat). . . . . . 154 

Cataract Creek . . . . . . . . 48 

Cedar, or kawhaka . . . . . . 8 

Cedar Creek, quartz-mines of . . 25-26, 145 

Track, rocks of . . 98, 99, 101 

Chlorite as rock-corustituent 82 et seq., 99, 122, 

132, 133, 134, 139, 140 

Chlorite-schist . . . . . . 83, 84 

Chromite . . . . . . 122, 125, 126 

Clays .. .. .. 107, 110, 150-151 

,, analyses of . . . . . . 150 

Clear or Donoghue Ci'eek, gold of 23, 24, 27-28, 152 
,, „ sandstone of . . 108 

Cleavage, slaty . . . . . . 98, 99 

. . 8, 15 

..117 

12-15 

. . 86, 87, 89, 136 



Clematis 
CUffy Head 
Climate 
Clinozoisite 
Clover, white 



Coal 



26, 31, 102, 103, 104, 105, 108, 151, 157 



„ analyses of . . . . . . 151 

Coal Creek, Upper Miocene rocks of 107, 108, 110 
coal of . . . . 26, 151 

Coal-formation . . . . . . 31, 102 

{See also Koiterangi Series.) 
Coal-mining . . . . . . '. . 26 

Coast. iS'ee Beach. 

Coastal plain, modern . . 11, 46, 118, 119 

Cobden limestone . . . . . . 102 

Cockayne, L. . . . . . . . . 7 

Collier Gorge . . . . . . . . 48 

Communication, means of . . 20-22 

Concentration of auriferous material 34, 113, 114, 

152, 153, 155, 156, 162 

Conglomerates, Koiterangi 102, 103, 104-105, 113 

„ reassorted and concentrated 

34, 113, 114 
Upper Miocene . . 31, 107, 109 
(iS'ee also Gravels.) 
Constitution HiU . . . . 24, 41 

Continental land, ancient 4, 5, 7, 31, 32, 34, 36, 37 
(See also Land, ancient, former, pre- 
Arahura. ) 
Conway Ridge . . . . . . 40, 69 

Cook, Mount . . . . . . 42, 44 

,. ,, rainfall in district near . . 13 

Copijer . . 123, 143, 144, 146, 156, 161 

Coprosma, various species of . . . . 8, 9 

Cormorant . . . . . . . . 6 

Corundum . . . . . . . . 124 

Cotton-plant, or mountain-daisy . . . . 10 

County Glacier . . . . . . 59, 61 

„ ' River . . . . . . 52, 161 

„ „ power from . . . . 161 

Cowhide Creek, fan of . . . . . . 66 

„ probable overthrust at . . 72 

Cox, S. H. 2, 16, 17, 30, 76, 96, 113, 131, 147, 154 
Crape fern . . . . . . . . 8, 29 

Creeping-plants . . . . . . 8, 15 

Cretaceo-Tertiary Formation . . 31, 102 

(iSee also Koiterangi Series.) 



167 



Cretaceous rocks, &c. , . . . 30, 31, 102 

Cromwell Subdivision, serpentine of . . 121 

Cropp River . . . . 48, 49, 160 

„ Pouoamu rocks of . . 124, 125, 129 

„ water-power from . . . . 160 

Oushed rock, zones of . . 68 et seq., 154, 161 

(See also Faults.) 

Crystal Creek .. .. .. 50,158 

' 'uckoo, long-tailed, or kohoperoa . . . . 5 

C\iJture . . . . . . 20-29 



D. 

Dairying . . . . . . 29 

Daisy, mountain- . . . . 10 

Daly, R. A. . . . . . . . . 130 

Decomposition of rocks . . 121, 123, 132, 139, &c. 

(See also Weathering, &c.) 
Deep leads .. .. .. 157,158,162 

Dcntalium, fossil . . . . 30, 76, 80 

Dental imn huiloni .. .. .,.80 

Denudation of land 34, 35, 42, 44, 47, 60, 103, 107, 

113, 114, 115, 143, 155 

(See also Rivers, Glacial erosion, 

Weathering. ) 

Depression of land 34, 35, 37, 68, 102, 107, 113 

„ areas of . . . . 71, 73 

Diabases .. .. .. ..139 

Dick Creek, rocks and minerals of 94, 148 

Dickson River .. .. .. 51,160 

Diedrich Range. . . . . . . . 39 

Dioritos (basic) .. .. 139,140-141 

,, rocks resembling . . 82, 87 

Dip, The (Saddle) . . . . 46, 58 

Distribution, former wider, of fossil- bearing 
rocks . . . . . . . . 80 

Distribution, former Nvider, of various Ter- 
tiary formations .. .. 103, 107, 114 

Doctor Creek and Valley . . 58, 74 

rocks and reefs of, &c. 87, 8S. 89, 90, 

92, 93, 133, 136, 144, 149 

Doctor Hill . . . . . . . . 41 

„ coal reported near . . 26, 103, 151 

„ fault near . . . . 70 

rocks of . . . . 132, 138 

Dolomite .. .. .. 120,122,123 

Donnelly Creek, gold in valley of . . 23, 26, 152 
rocks of. . 99, 107, 108, 110, 149 
Donoghue Creek. See Clear Creek. 
Donoghue Lagoon . . . . . . 65 

Donoghue's, auriferous sands and graveb 



at . . 
Dotterel, banded 
Doughboy Hill and vicinity 

„ granite of 

Douglas Saddle 

„ Stream, rocks of 
Dracophi/Uum, various species of 
Drainage adits . . 
„ captui-ed 
Dredging, gold-, &c. 
Drumraond, James 
Ducks, blue, grey. Paradise, &c. 
Duffer Creek 

„ gold in 

„ rocks of 

Dufler or Ounatai Lagoon 
Dunite 
Dykes, basic 
„ acidic 
(See also Aplite, Pegmatite.) 



23, 24, 27-28 

..6 

41,45, 116, 132 

132, 149 

45, .58 

83, 92 

. . 9, 10 

. . 27 

48, 56, 58 

24, 25, 28 

5 

6 

22, 52 

24, 153 

1.32, 133 

52, 64-65 

31, 120, 121-122 

30, 82, 138-142 

.. 82,131,133 



E. 

Earthquakes . . . . 70, 72 (footnote) 

Economic geology . . 143-158, 161-162 

(See also Culture, &c.) 
Edelweiss (New Zealand) . . . . 10 

Eels . . . . . . , . * * 7 

Electricity from water-power 27, 150, 158 ei seq. 

Elevation of land, &c. 3, 4, 35, 36, 37, 43, 7 1 et seq., 

103, 107, 113, 115, 155 

Emery . . . . . . . . 124 

Eocene rocks . . . . . . _ _ io3 

(See also Koiterangi Series). 
Epidote as rock-constituent 82, 83, 86 et seq 98 
99, 120, 122, 123, 127, 128, ISSetseq., 1S9 et seq. 
Epidote rocks . . . . . . 123, 127 

Epidotization of feldspars, &c. 86 et seq., 98,' &c. 
Erosion. See Denudation, Streams, Glaciers, 

&c. 
Erosion, base-level of . . . . . . 42 

(See also Peneplain.) 
Erosion, cycles or periods of 32, 42, 43, 113, 114 
Essex Glacier . . . . . . 53, 60 

„ immature valley of . . . . 60 

Evans Creek, alluvial gold in . . . . 24 

Evans Glacier . . . . 52, 59-60, 61, 118 

,, Mount . . . . . . . . 40 

„ Saddle . . . . . . . . 46 

Excelsior Claim (Ross) . . . . 26, 162 



Falls Creek, gold in . . . . . . 24 

,, granite of . . . . . . 149 

,, valley and rock- basin of 70,74,118 

Fan structure of serpentine (antigorite) . . 122 
Fans, creek . . . . 11, 66, 67, 117, 118 

Fantails . . . . . . . . 4 

Farmer Creek, quartz reefs of, &c. 26, 145 

Faults and faulting 30, 31, 41, 42, 43, 46, 64, 67, 
68-75, 79, 84, 87, 97, 98, 103, 
107, 108, 121, 122, 132, &c. 
Faults, reversed or overthrust 31, 43, 71-72, 97, &c. 
Faidt-scarps . . . . 46, 69, 70, 71, 72 

Fauna . . . . . . . . 3-7 

,, former land-extension indicated by 

3, 4, 5, 6, 34 

Felds])ar as rock-constituent 81, 82, 85 et seq., 98, 

99, 100, 105, lOG, 109, 112, 

124, 127, 128, 132 et seq. 

alteration of . . . . 81, 86, &c. 

(See also Epidotization, Silicification. ) 
Feldspar eyes . . . . . . . . 90 

Ferguson's, post and telephone office at . . 21 
Ferns . . . . . . . . 8, 9, 15, 29 

Finlayson, A. M. . . . . . . 1 

Fishes . . . . . . . . 7 

Five-finger, or patete . . . . . . 8, 29 

Flagstaff Hill, Upper Miocene sandstones of 108 
Flat Creek, rocks of . . 100, 101, 134-135 

Flats in Alpine valleys . . . . 61, 69, 74 

(See also River-flats, Rock-basins.) 
Flax (New Zealand) .. .. 9,11,29 

,, mountain- . . . . . . 9, 10 

Flood-plains .. .. .. 9,11,29 

(See also Plains, River-flats.) 
Flora .. .. .. .. .. 7-11 

,, former land-extension indicated by 

7, 8, 9, 15, 34 
Floimders . . . . . . . . 7 

Fluviatile gravels .. 32,115,116,118,151- 

153, 154, 155 

„ auriferous 22 et seq., 151-153, 

154, 155, 156, 162 



168 



Page 

Fluvio-glaciai gravels 32, 115-117, 118, 153, 155 

,, ,, auriferous . . 153, 155, 156 

{See also Gravels, Glacial deposits, &c. ) 

Folding, folding-directions, axes, &c. 30,*i31, 34, 

35-37, 43, 62, 63, 71, 77, 78, 97, &c. 

„ influence of older, on Alpine strike 

43 (footnote), 78 
Folding-periods . . 34, 35-37, 79 

Folds, overturned . . . . 69, 71, 78, 79 

Foliation or lamination planes 82, 98, 122, &c. 

(See also Schists.) 
Foothills . . . . . . 41-42, 44 

faulting and tiltmg of, &c. 41, 42, 70-71 
,, structure of . . . . 44, 71 

Foraniinifera . . 102, 104 et seq., 109 et seq. 

Ford Range . . . . . . . . 41 

Forest . . . . . . 7, 8, 9, 15 

,, tropical asfsect of . . . . 8, 15 

Fossils . . 30, 76, 79-80, 102, 104, 105 et seq. 

{See also Palseontology.) 
Fraser, C. . . . . . . 1, 12, 18 

Fraser Peak . . . . . . . . 41 

rocks of . . . . 132, 149 

Frew Saddle . . . . . . . . 45 

Fuchsia, or kotukutuku . . . . . . 8 

Fuchsite .. .. 124 (footnote), 164 

Fucoid casts . . . . . . 102. 108, 110 



G. 

Galvin, P. .. .. .. ..17.18 

Garnet 82, 83, 87. 88. 89, 93, 94, 110, 119. 136. 

137, 153 
Gentians . . . . . . . . 10 

Geological formatiorus, table of . . . . 33 

„ history . . . - . . 32-35 

„ surveys, ])revious . . . . 2 

Geology, outline of . . . . . . 30-37 

Glacial' deposits 2. 1 1, 32. 34. 35. 38, 42. 46, 59, 60, 
64, 65, 66, 104. 115-118, 153. 155. 156. &c. 
Glacial erosion, transportation, and deposi- 
tion. . . . 35, 47, 54, 55, 60-61. 74, 75, &c. 

Glacial epoch (Late Tertiary), unlikely . . 115 
„ topography 47. 48, 49, 50, 51, 52, 53, 54, 

55, 61, &c. 
Glaciation of Koiterangi age . . 34, 102, 104 

„ in Pliocene and Pleistocene periods 

35, 47, 11.5-118 
„ in Upper Miocene time . . 35 

,, modern .. .. 35, 118 

{See also Glaciers.) 
Glaciers 35, 38, 42, 48, 51, 52. .53, 55, 58-61, 

115 et seq., 153 

,, advance and retreat of . .35, (50, 115. 116 

cliff . . . . . . 51, 58, 59 

Glauconite .. .. 10.5. 110. Ill, n2 

Gneisses and giieissic schists 30, 32, 34, 41, 44, 71. 

76, 80-82. 8(5-93 
,, » *gc of . . 82 

,, „ dykes in . . 82 

„ „ inchisions of. in 

granite . . 130 

„ metamorpliism of 

82. 87, 131. 136 

origin of 30, 77.81.82, 

87. 88, 90 et -feq. 

,, „ possible gold in 153 

Godwit . . . . . - ■ . 6 

Gold 20, 22 et .ieq., 114, 119, 143 et seq., 151 el seq., 

161, 162 
„ discoveries of . . . . . • 22, 23 

„ ])rodiiction of . . . . 23 e< seq. 

„ source of alluvial .. ..114. 155-156 



Page 
Gold, alluvial, gold-bearing gravels, &c. See 
Alluvial gold, Auriferous^^alluvial de- 
posits, &c. 
„ -saving appliances . . . . . . 24, 25 

Gold Point (:Mungo River) . . . . 152 

Gondwana continent, ancient . . . . 34 

" Goodletite," or ruby rock . . 123, 124 

Goodlett, William ' . . . . . . 124 

Gordon, H. A. . . . . . . 2, 18, 145 

Gorges .. 38, 47 et seq., 54, 158 et seq. 

Grahen of Waitaha Valley . . . . 70 

Grade of rivers . . . . 54, 74, 158 et seq. 

Granite and granitic rocks 30, 31, 43, 71, 77, 87, 

88, 97, 98, 130-137, 147, 149, &c. 

„ gorges . . . . . . . . 48, 52 

„ intrusions. See Bo.sses. 
,, metamorphie influence of 98, 1(X), 130, 

131, 136-137 
„ pebbles, fu-st appearance of, in sedi- 
mentary rocks . . . . 109 

„ possible origin of . . . . 131 

„ reported auriferous . . . . 147 

(See also Tuhua Formation. ) 
Granite-gneiss mountains .. ..41.44 

Granitite . . . . . . 130, 133, 134 

Graphic intergrowth of feldspar and quartz 132, 133 
Grasses . . . . . . 7, 9, 10 

Grauwackes 25, 31, 82, 85, 89, 94-95, 98, 99-100, 

107. 109. Ill, 130, 135-136, 149 

„ brecciated jihase of . . . . 85 

„ inclusions of. in other rocks 82. 130, 

135-136 
Gravels . . 20, 22 et seq.. 32, 34, 45, 46, 

113-119, 151-158 
{See also Fluviatile, Fluvio-glaciai, Ma- 
rine, and Morainic Gravels ; Auriferous 
alluvial deposits ; Moutere (iravels. ) 
Grayling, native . . . . . . 7 

Grazing, grazing-land, &c. .. 11. 12, 2t) 

Greenland, Mount . . . . . .21, 41 

alluvial gold of. . 24,25,152 

„ ,, quartz lodes of 25, 145, 156. 162 

„ rocks of 24, 25, 96e^sc9.,107. 108 

(See also Ross and neighbourhood. Cedar 

Creek, &o. ) 

Greenland Series 25. 31, 34, 44, 71, 96-101, 115, 

131, 137, 144-147, &c. 

ageof .. .. ..31,96 

,, analyses of rocks of . . 101 

argillites of . . 25, 31, 98-99 

„ auriferous character of 96, 144 

„ coiTelation of .. ..31,96 

distribution of .. ..96-97 

faulting of 31, 70-71, 97, &c. 

grauwackes of 25, 31, 98, 99-100, 

131, &c. 

„ metamorphism of 31, 44. 71. 98, 

131. 1.37 
„ origin of rocks of . . 96 

„ petrology of . . 97-100 

,, quartz veins of . . 96, 14-1—147, 

156, 162 

,, strike or dip of . . 31. 44, 71, 97 

stnicture of 31. .34, 44, 71. 97 

Gregory, J. W. . . . . . . . . 36 

„ " Valley, ancient 38. 51. 58, 72. 81 

,, ,, ., overthrust of . . 72 

Greiseu-like veins .. .. .. 131 

Greville, R. P. . . . . . . 1,3. 159 

Grevmouth, rainfall at . . . . 13, 14, 15 

Gribben Flat . . . . . . 51, 73, 74 

Gribben's Homestead .. .. ..21,96 

„ quartz vein near . . 145 

Grimmond Creek, quartz vein in . . . . 144 

Grits and sandstones . . 102, 105. 107, 1()!», 110 
Gulls .. .. .. .. .. 6 



169 



H. 

Haast, Sir Julius Von .. 2, 16, 19, 30, 41, 44, 

47, 66, 76, 102, 115, 116, 117, 131, 147 

Hcematite as rock-coiistituent 88, 126, 136. 139, 

140. 141 



Hanging valleys 
Happy Valley . . 
Hare . . 

Harper, A. P. . . 
Harry Creek, rocks of 
Harry, Mount . . 



38. 47, 48, 55. 160. &c. 

22, 74, 118 

3 

13 

70, 84 

41, 45, 83 



Harvey Creek, ITpper Miocene sandstone of. . 108 
Hassock or carpet grass . . . . . . 10 

Hatter Creek, Upper Miocene sandstone of . . 108 
Hay, P. S. .. .. .. ..18 

Headover Creek, rock from . . 88-89 

Heave . . . . . . . . 69 

Hector, Sir James 2, 16, 17, 31. 32, 102, 114 

Hende's .. .. .. 21, 53 

,, dark schists near . . . . 83 

,, faults shown near . . . . 72 

Henley (Otago), old moraine near .. 116 

Hermitage, Mount Cook, rainfall at 13. 14, 15 

Heron, white, or kotuku . . . . 6 

Hinau . . . . . . . . 8 

Hitchin Range . . . . . . . . 40 

Hitchin's Beach, auriferous sands of . . 24 

Hochstetter, F. von . . . . 16. .3(), 44 

Hodson Creek, limestone of 103. 104, 105, 106, 

107, 110, 149 

Hokitika Bulletin, Subdivision, &c. 1, 2, 18, .30. 32, 

38, 77, 96, 120. 1.30, 131 

rainfall at .. .. 13, 14, 15 

,, (Jlacier (ancient) .. 116 

River, and tributaries 23. 47-50, 54. 56 

.. gold in 23. 143, 152, 162 

„ ., gorges of . . 48, 49 

„ rocks of 90, 132. 134, 135, &c. 

„ water-power of . . 160 

Valley, faults of . . . . 69 

Honey . . . . . . . . 29 

Hornblende as rock- constituent 81, 83, 85 et seq., 

110, 124, 128, 133 etfieq., 139, 140 

-biotite-granite . . 130, 133, 134 

„ -camptonit . . . . . . 139 

Hot Spring Creek 52, 63 

Hot Springs. See Springs, thermal. 

Howitt Terrace . . . . . . 50 

Humbug Creek, coal, quartz veins, or rocks of 

98, 100, 103, 133. 1.38, 144, 151 
Humphrey's Gully beds . . . . 113 

Hupiro, or karamu . . . . . . 8 

Huts, shelter . . . . . . 21 

Hutton, F. \V. . . 5, 32, 36, 37, 102, 1 15, 1 16, 131 
Hydrothermal action .. 78, 79, 84, 121, 128, 

137, 144, &c. 
(See also Metamorphism (thermal), Silici- 
fi cation.) 



I. 

lanthe Lake . . 16, 24, 35, 38, 63-64, 162 

,, alluvial gold near . . 24, 153 

Ice-falls . . . . . . 59, 60 

Igneous rocks .. 32,81,82,87,88,90,91,92,93, 

124, 136, &c. 
(See also Basic igneous rocks, Pounamu 
Formation, Tuhua Formation, &c.) 
Ilmenite . . . . 82, 86, 90, 136, 139 

Indo-Malay land-connection, possible . . 4, 34 

(See nlso Continental land.) 
Information, general . . . . . . 1-19 

Inframeta, Mount, rocks and minerals of 

94. 122, 149, &c. 

13 — Mikonui. 



Inhabitants 

Introduced fauna or flora 

Introduction 

Iron-oxides 

(See film Hiiematite, Magnetite.) 
Iron-pyrites. See Pyrite. 



Page 

.. 20 

3-4, 6, 7 

1 

99, 123, &c. 



Joints . . . . 98, 124, 138, 149 

Jones Creek and Flat, auriferous gravels of 

26, 152, 154-155 

,, ,. gold- production of . . 28 

Julius Creek, amphibole-schist of . . . . 85 

-lumbletop, -Mount .. .. ..39 

rocks and minerals of 121, 123, 
124-125, 148, 149 



K. 

Kahikatea, or white- ])ine . . 8, 9, 29 

Kaikouras (Marlborough), recent elevation of 

71, 72 
Kaka . . . . . . . . . . 5 

Kakajjotahi River . . . . 52, 54 

Valley 22, 29, 74, 118 

.. rocks from 136, 138 

Kamahi, or red-birch . . 8 

Kanieri Series . . . . . . . . 96 

Kaolinitic matter . . 90, 110, 128, 134, 136 

(See also Clays.) 
Karamu, or hupiro .. .. 8 

Kawhaka, or cedar . . . . . . 8, 9 

Kea . . . . . . . . 4, 5 

Kea Pa.ss 44, 45 

Kelly's Creek, annelid in rocks of . . . . 80 

Kidney fern . . 8 

Kiekie . . 8 

King fern . . . . 8 

Kingfisher . . . . ^ . 5 

Kirkland, Professor (Melbourne) 147 

Kiwi . . . . . . . . 4, 6 

Knobby Ridge . . . . . . . . 40 

Koekoea, or kohoj)eroa . . . . . . 5 

Koiterangi Hill . . 41, 70 

„ coal at . . 26, 105, 151 

,, ,, limestone and other rocks of 

98, 100, 104, 105, 149, &c. 
„ „ quartz veins at . . . . 144 

Series . . 31, 34, 35, 102-106 

„ age of .. 31, 35, 102-103 

„ coal of 35, 102, 103, 104, 105, 151 

„ „ conditions of deposition of 102 

„ „ conglomerates oif 35, 102, 103, 

104-105, 113, 114, 115, 155 

content of . . . . 102 

„ correlation of . . 102-103 

,, „ grits and sandstones of 102, 105 

limestones of 102, 103, 104, 105, 

106, 110, 149 

„ paleontology of . . 102, 104, 105 

„ petrology of . . 104-106 

„ ,. shaly rocks of . . . . 105 

„ ,. strike and dip of . . 31,103 

,, structure of . . . . 103 

„ „ tilting and faulting «f 31,74 

Koiterangi-Kokatahi Plain . . 20, 29, 46 

Kokatahi River. . . . 39, 47, 50, 62, 121 

Valley, faults of .. .. 69 

„ water-power of . . . . 158 



170 



Koromiko 

Kotuku, or white heron 

Kotukutuku, or fuchsia 

Kowhai 



L. 

Labradorite as rock-constituent 88, 91. 
Lacustrine deposits 
Lagoons 
Lakes . . 

„ ancient . . 
Lambert Glacier 

„ Mount 

„ River . . 
Lancewood, or horoeka . . 
Land, ancient extension of 4, 



Page 
8 
8 
8 
9 



134, 140, 141 

64, 118 

38, 64-65 

35. 63-64 

47, 64, 118 

..53.60 

..39,40 

..52. .53 



7. 31. .32. .34, 36, 

37. &c. 

„ former, to west of coast-line 31, 32. 33, 34, 

35,36,37,68.97,113,115,155 

,, pre-Arahura . . . . . . 131 

Land and soil, character of . . . .11-12 

Lands and Survey Department. Hokitika 2, 3, 22 



Lange Range 
Lark, European 

„ ground, or pihoihoi 
Larnach, Hon. W. J. M. 
Lateral moraines 
Laurentian protaxis of Canada 
Lead (metal) 
Leads, deep 
Leucoxene as rock- constituent 



40 
6 
4 
17 
.. 64. 117, 118 
32 
. . 144 
. . 157, 158, 162 
82. 83. 86. 87, 90. 
91. 92. 1.36, 139 
Lewis, Isaac . . . . . . 147 

Lichens . . . . . . . . 10 

LUy, mountain- . . . . . . 10 

Lime, caustic, agricultural value of 11, 149 

„ manufacture of nitrate of . . . . 150 

Limestones 35, 102 et seq., 110, 111, 149-150 

„ analyses of . . . . . . 150 

Littoral deposits . . . . 105, 107 

Lizards . . . . . . . . 7 

Lord Glacier . . . . . . . . 53, 60 

„ Range . . . . . . . . 40 

„ River . . . . . . . . 53 

Louper, Jacob, discovery of gold by . . 22 

Slount . . . . . . 39 

„ Stream (Canterbury), grauwacke of 95 
Lycopodium . . . . . . . . 8, 9 

Lyes, Lake . . . . . . . . 64 



M. 

McGowan, Hon. James . . 
McKay, Alexander 2, 17, 18, 30, 32, 
96, 113, 114, 115, 124, 131, 
McKenzie Glacier 
Maclaurin, J. S. 
McLeod Terrace, clays and gravels of 

McLeod's Terrace Sluicing Claim . . 

Macmillan Creek, talcose rocks of 
Mair Saddle 
Makomako (tree) 
Makomako, or bell-bird 
Magma, acidic . . 
Magnesian solutions 

(iSee also Hydrothermal action.) 
Magnesite as rock-constituent 120, 







18 


36, 68, 71 


,76, 


155, 156, 


157 


48, 5c 


t, 61 


..3 


151 


71, 107, 


108, 


150, 


151 


28, 108, 


117, 


153, 


157 




123 






46 




, 


8 






4 






131 


31, 69, 


&c. 


122, 1 


23, 


124 



Page 

Magnetite as rock-constituent 82, 83, 84, 86 et .leq., 

98, 99, 100, UQet seq., 128, 

133 et seq., 139 et seq. 

„ octahedrons . . . . 84, 122 

,, titaniferous 82 et .seq., 139 et seq., 153 

Maitai Series . . . . 31, 76, 77, 80. 96 

{See also Greenland Series.) 
Mammals . . . . . . . . 3-4 

Manganese oxides . . . . . . 123 

Manuka, or tea-tree . . . . . . 8. 9 

Maori hen, or weka . . . . . . 6 

Maple, red and white . . . . . . 8 

Mapourika, Lake, Greenland rocks near . . 97 
Margarite . . . . . . 124 (footnote) 

Marine gravels . . . . 32, 35, 116, 118, 119 

{See also Beach-.sands.) 
Marshall, P. . . . . . . 18, 36, 43 

Matai, or black-pine . . . . . . 8, 29 

Mathias Pass .. .. .. ..21.44 

,, lode near . . . . . . 143 

Mesh structure in serpentine . . . . 125 

Meta Ridge .. .. .. ..40,69 

„ Saddle .. .. .. ..45,69 

Metalliferous veins . . . . 143-147 

(See also Quartz veins.) 

Metamorphism, dynamic or regional 30, 31, 69, 

71, 77, 78, 79, 82, 83, 84, 85, 

87 et seq., 136, 137, 139 

hydrothermal 31, 69, 79, 83, 84, 

101, 121, 128, 129, 130, 131, 137 

thermal .. 98, 100, 123, 128-129, 

130, 131, 136-137 

Metamorphosed rocks, doubly . . 83, 84—85 

Metasomatic changes . . . . . . 137 

Meteorology. See Climate, Rainfall. 
Meirosideros, various species of . . 8, 9, 10 

Mica as rock- constituent 81, 83, 84, 85, 132, 137, 

140, &c. 
(See also Biotite, &c.) 
Mica-schists . . . . . . . . 83-85 

Mica-quartz-schists . . . . . . 83 

Microcline . . . . . . Ill, 133, 134 

,, feldspars resembling . . 81, 140 

Mikonui Glacier, ancient " . . 117, 153 

,, River and tributaries . . . . 51 

„ ,. drainage captured by . . 58 

„ ,, post and telepone office near 21 

„ ,, power from . . . . 160 

„ Spur, schist of . . . . . . 94 

„ Sugarloaf .. .. ..41,77 

Vallev.. .. .. ..29,74 

Valley, rocks of 81, 88-89, 108, 109, 110, 

111, 136 
,, Water- race . . . . . . 28 



Minerals, list of . . 
Mingimingi, or black scrub 
Mining 

,, areas, special 
Miocene Beds, Upper . . 31, 35, 
„ age of 



163-164 

9 

..22-28 

.26-28,153-155 

74, 103, 107-112 

..107 

arenaceous limestone of 111 

clays and calcareous 

mudstones of 31, 107, 109, 

110, 150-151 

coal of . . 108, 151 

conditions of deposition 

of .. ..107 

conglomerates of 31, 107, 109 
content of . . . . 107 

correlation of 32, 107 

distribution of 107-108 

faulting of . . 31, 72, 108 
general characters of ;109-1 10 
grauwackes of 107,109,^,111 
grits and 8andstones''of 

31, 107, '109, 110 



Ill 



Miocene Beds, UpjK'r, involved in Alpine over- 
thrust . . 72, 108 
„ ,, palaeontology and fossils 

of 107,108-109,110 

„ petrology of 110-112 

„ ,, reassortmcnt of .. 113 

„ ,, strike and dip of . . 108 

„ ,, structure of . . 108 

Miro . . . . . . 8 

Misery, Mount . . . . . . . . 41 

„ rocks of . . 81, 132, 138, 149 

Mont d'Or Claim . . 20, 27, 116, 118, 153 

Moose, Canadian . . . . 4 

Morainic and fluvio-glacial gravels 115-118 

(.S'fe alfo next heading.) 
Moraiiiie deposits 2, 11, 15, 32, 34, 38, 42, 46, 54, 
59, 60, 61, 64, 65, 66, 74, 115-118,153, 155, 156 
(iS'ee alxo Glacial deposits, &c.) 
Morainic hills . . . . . . 42, &c. 

Moraines, protective action of, on river- 
channels .. .. .. ..54,74 

.More|>ork, or ruru . . . . 5 

.Morning Star Claim (Ross) . . 26, 162 

Mosquitoes . . . . . . 7 

Mosses . . . . • 8, 9, 10 

Mountain- plants. See Alpine and suhalpine 
llora. 
ranges, ancient .. ..34,37 

,, slopes, .soil of . . . . . .10, 12 

Mountains and hills . . 34, 39-44 

{See also >50uthern Alps, Foothills, &c.) 
Moutere Cravels 32, 35, 113-115, 116, 153, 

155, 157, 162 
„ age of . . . . . . 114 

,, auriferous character of 114,155, 

157, 162 

.. 114 

.. 114 

.. 113 

.. 114 

35, 114-115 

35, 114,116, 

153, 155, 162 

,, structure of . . 114 

tilting and faulting of 32,114 

Moutere River (N'eLson), ancient gravels of . . 113 

(hypothetical ancient) 32, 35, 56, 

57, 115, 155 

Mudstone . . 109 

MuUins Creek . . 50, 54, 159 

Mungo ( dacier . . . . . . 58 

River .. 47,48,56 

,, ,, gold in . . . . 152 

,, hot springs of . . 62-63 

Saddle .. 4,21,44,45,77 

„ „ fossils near . . 79-80 

Valley, fault of . . . . 69 

„ „ grauwacke from . . . . 94 

Murray Saddle . . . . . . 45, 58, 118 

Muscovite as rock- constituent 81, 85, 88, 90, 93, 

94, 98, 100, 111, 132et.ss9. 

plates . . . . 133 



correlation of 
distribution of 
general account of 
general characters of 
origin of 
reassortmcnt of, &c. 



\. 

Needlewood 

Neinei, or snow-tree 

Nelson, granites of 

morainic deposits of 
Moutere Gravels of 
jx-neplain 

Nephrite, or pounamu 

Net structure of serjientine 



. . 9, 10 

. . 9, 10 

.. 131 

116 

35, 113, 114 

43 

.. 120 

122 



Page 
New Guinea, probable laud- connection with 

4, 34, 37 
New Zealand, isolation of . . . . 3, 4 

,, biological evidence of former 

extension of 3 et seq., 15, 34, 36 
., former continental extension of 

4, 5, 7, 31, 32, 36, 37 
Non-schistose rocks (Arahura Series) 85, 94-95 

Northcroft Saddle . . . . . . 46 

North Westland or Wainihinihi peneplain 

34, 35, 42-43 
Nuts, possible pyritised . . . . . . 105 



0. 

Obsequent streams 
Okuru, rainfall at 
Old Man Bottom 

(See a/so Moutere Gravels.) 
Olearia, various species of 
Oligocene rocks , 

(See also Koiterangi Series.) 
Gligoclase as rock- constituent 

99, 
Olivine as rock-constituent 



. . 73 (footnote) 

13,14,15 

.. 113,155,162 

8, 9, 10 
102, 103 

81, 82, 88 i-txc.q., 
133, 134, 136, 140 
122, 125, 138. 139, 
140, 141 
122, 129 
138, 139 
. . 139 
88 



,, alteration of, to serpentine, &c. 
„ -basalt . . . . . . 

,, -diorite 
Ojjen Creek, rock from . . 
Orogenic movements 43, 97, 131, 136, 139, &c. 

(See also Southern Alps.) 
Orthoclase as rock- constituent 81, 86, 98, 99, 111, 

132, 133, 134 
Oscillations of land . . . . . . 107 

(.S'ee also Depression, Elevation.) 
(Jsmers and party (Ross) . . 25, 144, 145 

(Jtago peneplain . . . . . . 143 

., Central, rocks, &c., of . . 79, 116, 121 

Western, gnelssic rocks of . . . . 32 

Otira, rainfall at . . . . 13, 14, 15 

Otokaia (Otago), old moraine near .. 116 

Ounatai or Duffer Lagoon . . 52, 64-65 

Overfolding .. .. 44,69,71,78,79 

Overthrusts on western side of Alps 43, 68, 71-72, 

87, 97, 103, 108, &c. 
,, involvement of Upper Miocene 

beds in . . . . 72, 108 



New Caledonia, probable land-connection with 4, 5 



Palaeontology . . 
Paradise duck . . 
Parakeet, green . . 
Park, James (Hokitika) 
Park, (Professor) James 
Park Glacier 
Park Stream, glacier of 
Passes and saddles 
Patete, or five-finger 
Peneplain, ancient 
Pepper-tree 
Pericline twinning 
Petrels 
Petrology, general 

special 86-95, 
Phalacrocorax, affinities 

s])ecies of 
Phyllites 
Physiography . . 



79-80, 104, 108-109 

6 

5 

3 

43, 76, 102 

48,59 

.. 58 

44-46 

.. 8,29 

34, 35, 42-43 

8 

HI, »& et seq., UO 

6 

. . 80-85, 97-99, 104-105, 

109-110, 114 

99-100, 105-106, 110-112 

of New Zealand 

6 
83, 84 
38-67 



172 



Page 
Picotite . . . . . . 122, 125 

Pigeon, New Zealand . . . . . . 5 

Pigeon Hill . . . . . . 41, 70 

Pine, red, black, white, silver, yellow, moun- 
tain . . . . . . . . 8, 9, 10 

Plagioclase as rock-constituent 81, 82, 88. 09, 105, 

111, 133, 134, 139, 140 

{See also Feldspar.) 

Plains 

Plan of work 
Plant-life 

{See also Flora.) 
Plant-remains . . 
Platinum 
Pleistocene beds 

,, sandstone, possible 

Pliocene beds . . 

(iSee also Moutere Gravels 
posits. ) 
Pliocene, Late, and Pleistocene deposits 
Ponga (fern) 
Porphyrites 

Post and telephone offices 
Pothole Creek, L'pper Miocene rocks of 
Pounamu Formation 31, 69, 
129, 143, 144. 147, 
Pounamu Formation, age of 

,, content of 



46-47 

• .. 2-3 

.. 7-11 

. . 102, 104, 108 

143, 144, 156, 161 

.. 113.115-118 

..110 

113-118 

Morainic de- 

11;5-118 

8 
.. 139 
20,21 
109, 111 
4, 77, 83, 84, 120- 
148. 149, 156, 161 
120-121 
. . 120 
correlation of 120-121 

distribution of . . 121 

economic resources of 143, 
144, 147, 148, 149, 156, 161 
metamorphic influence 

of 83, 84, 128-129 

metamorphism of . . 121 
miscellaneous rocks of 

123-124, 127 
mode of occurrence of 120 
peculiar igneous rock of 

124, 127-128 

petrology of 121-128 

pyritic veins- of .. 144 

quartz veins of . . 143 

serpentine of 31. 74, 122, 

125, 126 

serpentine-dunite of 121-122. 

125-126 

serpentine- schist of 122-123 

sills of ..31, 120 etseq. 

talc and asbestos of 120 et 

seq.. 147-149 

talc-.serpentine and talc- 

31, 123, 124-125 

. . 48 

48. 50 

8, 29 

15()-158, 161, 162 

26, 27 

42, 77 

77. 118, 132, 149 

6 



rocks of 
Price Flat 

,, River 
Prince of Wales's feather fern 
Prospecting . . 23, 24, 25, 26 
Pumping machinery 
PurceU Ridge . . 

„ rocks of, &c. 

Putoto, or swamp-rail 
Pyiite as rock-constituent 82 et seq., 88 et seq., 
99, 105, 110, 111, 120, 122 et seq., 133 rf.sej., 139 
Pyrite as vein- constituent . . 143 et seq. 

„ hardened and distorted by ]>ressure 85, 129 
PjTitic veins . . . . 144 

Pyroxene . . . . .90, 135, 136 

(See also Augite.) 
Pyrrhotite . . . . 140, 141 



Q. 

Quartz as rock-constituent 81 et .seq., 98, 99, 100, 

105, 106, 109 et .seq., 120 et seq., 

132 et seq., 139, 141 



Quartz, auriferous 
Quartz-diorite (basic) 
Quartz-mica-schists, &c. . . 
Quartz mining, auriferous- 
Quartz-schists 



Page 

143 et seq. 

. . 139, 140-141 

. . 83 

25-26, 144 et seq. 

84 



Quartz veins . . 25, 26, 85, 96, 143-147, 153, 

1.54, 156, 161, 162 

bedded . . 143, 144 

Quartz replaced by calcite . . 105, 111, 112 

,, epidote . . . . 98 

Quartzite . . . . . . 30, 85 



R. 

Rabbit 

Raho-Taiepa Stream 
Railway 
Rainfall 

,, run off. . 
Ramsay Glacier 
Rangitoto Range and Mount 



.. 52, 119, &c. 

20, 29 

12, 13, 14^15, 160 

. . 160 

61 

22, 24, 26, 41 



alluvial gold of 

24, 153, 156 

Rangitoto Range and Mount, quartz veins 

and rocks of 96, 97, 100. 101. 1.32, 134-135, 137, 

146-147, 149, 153, 156, 162 

Rangitoto Silver-mine . . 16, 26, 146-147, 156 

vein of 137, 146-147, 156 

Rata . . . . . . .'.5, 8, 9, 10, 15 

Rata and beech zone . . . . . . 8, 9 

Reassortnient of conglomerates, gravels, &c. 

34, 113, 114, 115, 116, 118, 152, 

153, 155, 156, 162 

Recent deposits. . 32, 35, 113, 118-119, 151-156 

{See also Gravels, Talus, &c.) 
Recrystallization of rocks 82, 87 etseq., 136, 137 

(.See also Metamorphism.) 
Red-bills . . . . . . . . 6 

Red Hill (South \A'estland), serpentine of . . 121 
Red-pine, or rimu . . . . 8, 15, 29 

Redman Creek, Upper Miocene rocks of 108, 109 
Reefton, auriferous rocks of . . . . 144 

rainfaU at . . 13, 14, 15 

Reid, R. C. .. ..17 

Rejuvenation of stream-action . . . . 61 

Reptiles . . . . • . . . 7 

Resorption border of liornblende . . 81, 89 

Rhodonite . . . . . . . . 123 

Ribbonwood, lowland and mountain 8, 9, 10 

Rift vaUey . . . . . . . . 70 

Rimu, or red-pine . . . . 8, 15, 28 

Ritchie, J. . . . . . . . . 1 

River and creek gravels, auriferous 151-153 

{See also Auriferous gravels.) 
River-basins or watersheds, areas of 55-56 

,, courses, ancient . . . . 56, 58, 115 

,, connection with faults, &c. 73—74 
capture . . . . . . 48, 56 

River-fiats 9, 20, 29, 38, 46, 47, 50, 51, 52, &c. 

„ plant-assemblage of . . . . 9 

River-gravels. See Fluviatile gravels, &c. 
River-terraces .. .. 11, 35, 50, 51, &c. 

Rivers . . «. . . 38, 47-53 

„ erosion by 35, 47, 55, 60, 61, 74, &c. 

,, gorges of . . . . 38, 47, et seq. 

„ grades of . . . . 47, 54, 74 

,, rejuvenation of . . . . 61 

„ valleys of 38, 47 et seq., 117, 118, &c. 

,, volumes of . . 56, 57, 158 et seq. 

„ waterfalls and cascades of . . 38, 47 et seq., 

53-54, 158 et seq. 
Roa, or great spotted kiwi . . . . 6 

Road-metal . . . . . . . . 151 

Roads and tracks . . . . 21—22 

Roberts, G. J. . . . . . . . . 3 



173 



Page 
Robin, South Island . . . . . . 4 

ifoc/te /«oh/o« nee, Koit«rangi a supposed .. 41 

Rock-basins . . . . 35, 47, 61, 74, 75, 158 

,, possible deep leads in . . 158 

Rock-wTen . . . . . . . . 5 

Ross, Township of . . . . . . 20 

Ross and neighbouihood, auriferous deposits 

of 2, 1(5, 23, 24, 20-28, 152, 154-155, 157, 162 
Ross and neighbourhood, quartz veins of 

25, 144, 145 

Ross and neighbourhood, rocks of, &c. 98, 99, 107, 

108, 110, 114, 116, 118, 149, &c. 

Ross Flat . . 2(>-27, 152, 154-155, 162 

,, Goldfields Company . . . . 27 

Ross United Companj', claims and shaft of, &c. 

27, 154 

Ruby . . 123, 124, 156, 161 

Ruby rock, or ' goodletite " . . 123, 124 

Rum, or morejiork . . . . . . 5 

Rutile as rock-constituent 82, 86 el neq., 94, 

133, 134, 135 



S. 

Saddles and passes 
Sagcnite 
■Sale (ilacier 
Sandhills 
Sandpipers 
Sands, beach 
Sandstones and grits 
Sawmilling 
Sawtooth Ridge 
Scarps, fault- 
Scenery 
Schistosity, development of 



See Beach- sands, 
81, 102, 



Slate Creek, Upper Miocene rocks of 



44-46 
86, 89, 94, 133, 135 
48, 58 
65» 119 
6 
, Black-sands. 
105, 107, 109, 110 
. . 29 
.40 
46, 69. 70, 71, 72 
]r>-16 
81, 89, 92, 93, 94, 
98, &c. 
(See alio Schists.) 
Schists, schistose rock.s, &c. 30, 32. 70, 80 95 

(iSW also Mica-schists, (Sneis-tes, &c.) 
Schists, dark . . 30, 81, 82-83, 86-93 

Sequence of geological formations 30-32 

Sericite . . 81, 83, 88, 90, 133, 1.34. 136 

Serpentine as mineral 82, 91, 92, 99. 122 H seq., 

136. 139, 141 

as rock 31, 74, 84, 120 et seq.. 129, 149 

,. derived from olivine 125. 129 (note) 

Serpentine Creek, rocks and minerals of 69, 121, 

122, 123, 129 (note), 148 

pvritic vein of . . . . 144 

Seri)entine-dunite " . . 120, 121-122, 125-126 
-schist 69, 120, 121, 122, 129 (note) 

-talc. See Talc-serpentine. 
Serpentinization . . 122, 125, 127, &c. 

Shag, black . . 6 

Shales and shaly rocks . . . . 105 

Shearer Creek, faulting in . . . . 71 

,, vein of . . . . . . 146 

Shore-line . . . . 65, 66 

Silica deposited by action of algae . . . . 62 

Siliceous solutions . . . . 62, 128 

(.S'ee fdso Hydrothermal action.) 
Silioification of feldspars . . 83, 88 el seq., 99, 

135, 137, &c. 

of rocks . . 79, 82, 83, 84, 88, 89, 

94, 128, &c. 

Sills of Pounamu Formation 31, 79, 120 et seq. 

Silt, lacustrine . . . . . . . . 118 

Silver . . . . 26, 143, 144, 145, 146, 156, 161 

Silver-eye, or blight- bird. . . . 4 

Silver- mining . . 26 

Silver- j)ine . . . . 8, 29 

Skev, William . . 26, 124, 146, 147 

Slate, rocks resembling . . . . 85, 98, 99 

(See also ArgiUites.) 



Page 

74, 109, 110, 

111 

.. 146 

66-67, 70 

24, 25, 27 

.. 154 



„ quartz vein of 

Slips .. 

Sluicing, hydraulic and ground 
Smith and party (Ross), claim of 
Smith Gorge, rock of . . . . . . 88 

Smyth Creek (tributary of Totara) 51, 74 

„ Miocenerocksof 74, 108, 109, 110-111 

,, Range . . . . . . . . 40 

„ Saddle . . 

,, Stream (tributary of Wanganui) 
Snow . . . . . . . . 11 

piak 
„ faU 
- fields . . 35, 39, 61 



. 46 
53, 161 
45, &c. 
11 
12, 115 
62, 115 



„ former extension of . . 39, 61, 115 
Snow-tree, or neinei . . . . . . 9 

Soil, character of . . . . 10, H, 12 

Sollas, W. J. . . . . . . 18, 122 

Sound, or arm of sea, ancient .. 35,107,110 

Southern Alps 2, 10, 12, 34, 35, 36, 38, 39-40, 42, 

43, 44, 68 et seq., 107, 113, 115, 143, 155, 156, &c. 

Southern Alps, age of . . . . 34, 36, 37 

denudation of . . 35, 43, &c. 

elevation of 34, 35, 37, 43, 72, 107, 
- 113, 115 
faults of . . 43, 68-70, 71-72, &c. 
folding and structure of 34, 36, 37, 
43-44, 71, &c. 
gold of . . . . 143, 155, 156 

mode of formation of . . 43 

47, 74 
10 
11 
. . 89 



., rock- basins of 

" Spaniards," or spear-grass 
Sphcerella nivalis 
Sphene 

(See also Titanite.) 
Springs, cold 

„ thermal and mineral 
Staurolite 

Stones, building and ornamental . . 
" Stoj)ing " caused by igneous intrusions 
Stout Glacier 



. . 48, 62, 65, 160 

60, 62-63, 68, 69, 70 

137 

149 

130 

58 



Strain in rocks, evidence of . . 82, 87 et seq. 

(See also Schistosity, &c.) 

Stream-capture . . . . 48, 56, 58 
erosion . . . . 35, 47, 55, 60, 61, &c. 

(See also Rivers.) 

Streams, subglacial erosion by . . 60, 61 

Structure, general geological . . 30-32 

Styx or Browning River . . 39, 47, 50 

Sul)alpinc zone, flora of . . . . 8, 9-10 

Subschistose rocks . . . . 85 

Subsidence of land. See Depression. 

Suess, E. .. .. 36,43,71,79,130 

Sulphuretted hydrogen . . . . 62, 63 

Summary of mineral resoui'ces, &c. 161-162 

Supplejack . . . . . . . . 8 

Sufvey, methods of . . . . . 3 

Swamps . . . . . . . . 9, 11 

Swamp-hen, or pukeko . . . . . . 6 

Swamp-thrush (swamp-rail) . . . . 6 

Swans, black, or Australian . . . . 6 

Swiss Republic Mining Company, claim of . . 25 

Syenite, rocks resembling . . . . 87 

Syntaxis of folding-directions . . 36, 37 



T. 

Table of geological formations . . . . 33 

,, river-volumes . . . . . . 57 

Tables of rainfall, rainy days, &c. . . 14, 15 

Taipo Hot Spring ' . . . . . . 62 

Talc 31, 68, 84, 120 et seq., 139, 141, 147-149, 156 



174 



I'age 

Talc harder than iioirnal .. 123, 124 

,, -rock, talc-actinolite, talc-serpentine 31, 123 

„ -schists . . . . . . 68, 84, 128 

Talus .. .. .. 11, 66,67, 117, 119 

„ resemblance of, to moraine . . 66, 118 

Tanekaha . . . . . . . . 8 



Tangiwai, or bowenite 
Tauhou, or blight- bird 
Teal, black and grey 
Teal Tarn 
Terminal moraines 
Tern . . 
Terraces, river- 
Thermal springs 
Thrush, European 
,, South Island 



. . 124 
4 

6 

64 

59, 64, 117, 118 

6 

46, 47, 50, 51, &c. 

50, 62-63, 68, 69, 70, 72 

. . 4, 6 

4 



Thrust-faults 31, 43, 71-72, 108, 130, 131, &c. 

Tiltmg, warping, &c. 31, 72-73, 74, 75, 103, 108 
Timber, timber industry. . . . 11, 28-29 

Titanite 82, 83, 86, 87, 89, 93, 94, 140, 141 

(See also Leucoxene.) 
Toaroha Canyon . . . . 50, 159 

„ Hot Spring . . . . . . 62 

,, Range 

„ River . . 

„ ,, cascades and rapids of 

,, ,, water-power of 

Saddle.. 

„ lode near 
Valley, faults of 
Toetoe 

Tom Creek, asbestos of . . 
,, faulting in . . 

Tomtit 

Topographical work 
Torlessiu mackayi 

{See also Annelids.) 
Totara (tree) 
Totara Forks, gold at 
,, Lagoon . . 
„ River and tributaries 
,, ,, gold in valley of 

„ valley, rocks of, &c. 86-87, 107 e< sej. 

., ., ,. quartz veins of . . 145 

Saddle .. .. .. 46, 58, 117 

Tourmaline . . . . 133, 136, 137 

Tracks, foot and bridle . . . . 21, 22 

Tree-ferns . . . . . . . . 8 

Trees. See Timber, Flora. 

Tremolite as mineral . . 85, 91, 120, 123 et seq. 

Trout, introduced and mountain . . . . 7 

Truran Pass . . . . . . 46, 118 

Tuhua Formation 30, 31, 43, 71, 77, 97, 130-136 
age of . . 30, 130 

aplite of . . 130, 133 

biotite-granites of 130, 133, 149 
bosses of 30, 31, 43, 71, 77, 97, 
130 e< seq. 
„ content of . . . . 130 

,, correlation of . . . . 131 

distribution of . . 131-132 

„ gneissic rocks excluded 

from .. ..130 

„ hornblende- biotite-granites 





of .. 




. . 


.. 133 


" 


metamorphic 


effects of 


82, 98, 
136-137 


„ 


mode of occurrence 


of 






30, 


130-131 


9J 


origin of 




.. 131 


„ 


pegmatite of 






130, 133 


,, 


petrology of 






132-136 


Tui, or parson- bird 






4 


Tuke River 


rocks of 
water-power of 






51, 160 
91, 138 
.. 160 



Tussock 

Tutu, lowland and mountain 



u. 



Page 
. . 9, 10 
8, 9, 10 



Ulrich, G. H. F. . . . . . . 124 

Ultra- basic rocks . . . . 31, 120 e< seq. 

{See (dso Pounamu Formation.) 
Unconformities . . 30, 31, 32, 77, 102. 103, 114 

Undulose extinction .. .. 81,82,94 

U|)Iift of land. See Elevation. 

Uralite . . . . . . 90, 128, 136 

Urquhart's, post and telephone office at . . 21 ■ 
U-.shaped valleys 38, 47 et seq., 55, 61, 74, &c. 





39 


Valencianite 


82, 127 




50, 158 


Valleys. See Rivers, Hanging 


valleys. 


5 of 50 


54, 158, 


U-shaped valleys. 






159 


Van Hise, C. R. 


.. 137 




158-160 


Vane Stream and Valley . . 


..52,53 




.. 45 


Vanina Stream, rocks of . . 


83, 92-93 




.. 143 


Veins, metalliferous 


143-147 




.. 69 


{See also Quartz veins.) 






. . 9, 10 


Veronica 


21, 98, 99 




.. 148 


(See aho Cedar Creek.) 






.. 69 


Vincent Creek . . 


48, 50, 58 




4 


Violet . . 


.. 10 




1, 2-3 


Viridite 


110,111 




.. 80 


Volcanic glass . . 


139, 140, 141 






rocks . . 32, 81 (footnote). 


82, 91, 92, 139 




8 


(See al.so Basic dykes.) 






24 


Volumes of rivers, table of 


.. 57 




51 


Von Haast. See Haast. 






50, 51 


Vulcanism, period of 


..32,82 


'. '. 23, 


145, 152 







w. 



Waikoik 


oi ('reek 


52 


Wainihinihi peneplain 


. . 42 


(See 


ahn peneplain.) 




Waitaha Hluff (Bold Head) 


22, 42, 65, 66, 117 


,, 


Glacier, ancient 


42,117 


,, 


Plain . . 


. . 46 




River and tributaries 


..51-52,160-161 




„ Little 


. . . . 52 


,, 


,, waterfalls and 


ra))ids of . . 54 




water-power of 


160-161 


,, 


Slip . . 


66-67, 70 


,. 


Sugarloaf 


22, 96, 97, 100, 101, 



118, 133, 135 

Valley 20, 22, 46, 51, 70, 74, 1 18, 121 

settlement in .. ..20,22 

Wanganui Bluff . . 15, 22, 65, 66, 117 

Glacier, ancient .. 42,117,153 

Plain . . . . 20, 46, 47 

,, ,, settlement of . . . . 20 

River and tributaries 22, 52-53, 54, 161 
„ ., navigability of . . . . 53 

,, ,, water-power of . . . . 161 

VaUey . . . . 53, 63, 70, 161 

,, ., faults and crushed rock of 

63, 70, 72, 161 
,, ,, hot springs of .. ..63,72 

Warping, &c. . . . . . . 72-73, 74, 75 

(See also Tilting.) 
Wataroa Subdivision . . . . . . 2 



175 



Waterfalls and cascades . 

{See also Rivers.) 
Water-power 
V\'ater-races 

Wax- or white-eye (blight- bird) 
Weasel 



Page 
53-54, 158, 159, 160 



27, 158-161, 162 

. . 28 

4 

.. 3,4 



121,132,139 

145 

6 

2 

158 



Weathering of rocks . . 60, 84, 1 1 3 

Weir Creek, quartz veins of 

Weka, or woodhen (South Island) 

Westland Divi.sion, South 

Whakarira Ciorge . . . . 50: 

„ rocks and minerals of, &c. 

84, 121, 123, 144, 148 

„ ^ cupriferous vein near . . 144 

Whaleback Hill.. .. .. 24,42,162 

Whio, orpjhie duck . . . . . . 6 

Whitcombe, Henry, explorations by 22-23, 47 

Mount . . 39 

Pass . . . . 4, 21, 44 

River and tributaries 47, 48, 160 



iold in 



23, 143, 152, 162 



,, water-power of 
Valley 

faults and slip of 
Whitebait 

White- pine, or kahikatea 
Wilberg Mount and Range 

„ Stream, amphibole-scliist of 



160 

48, 53 

66,70 

7 

8, 29 

40 

85 



Wilkinson Glacier 


48, 59, 61 


„ River 


48 


William Tell Jlining Company 


25 


Woodhen, or weka 


6 


Wren, rock- 


5 


Wren Creek, hot spring of 


..50,'62 



YeUow-pine 



Zala, Antonio (prospector) . . 26, 145 

„ Pond .. .. .. ..64,70 

Zala's battery . . . . . . 21, 26, 145 

Zircon . . . . 82, 83, 86, 87, 88, 110, 119, 

133 et seq., 152, 153 
Zit Saddle . . . . . . . . 45 

Zoisite. . . . . . 82, 83, 86, 87, 124, 127 

(See also Clinozoisite. ) 
Zonary structure in feldspars . . 140, 141 

Zone or belt, auriferous . . . . 143, 161 

Zones of crushed rock . . 6^ et seq., 154, 161 



By Authority : John Mackay, Govemme.t Printer, Wellington. — 1908. 



[1,500/5/08-5760 



6914? 74 




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